Organic electroluminescent materials and devices

ABSTRACT

Compounds comprising phosphorescent metal complexes comprising cyclometallated imidazo[1,2-f]phenanthridine and diimidazo[1,2-a:  1′,2 ′-c]quinazoline ligands, or isoelectronic or benzannulated analogs thereof, are described. Organic light emitting diode devices comprising these compounds are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of co-pending U.S. patent applicationSer. No. 14/744,535, which is a division of U.S. patent application Ser.No. 14/500,332, filed Sep. 29, 2014, now U.S. Pat. No. 9,065,063, whichis a division of U.S. patent application Ser. No. 14/277,979, filed May15, 2014, now U.S. Pat. No. 8,889,864, which is a division of U.S.patent application Ser. No. 12/908,138, filed Oct. 20, 2010, now U.S.Pat. No. 8,766,529, which is a division of U.S. patent application Ser.No. 11/704,585, filed Feb. 9, 2007, now U.S. Pat. No. 7,915,415, andclaims the benefit of priority of U.S. provisional Application No.60/772,154, filed Feb. 10, 2006; U.S. provisional Application No.60/856,824, filed Nov. 3, 2006; and U.S. provisional Application No.60/874,190, filed Dec. 11, 2006, the contents of which are incorporatedherein by reference in their entirety.

RESEARCH AGREEMENTS

The claimed inventions were made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: The Regents of the University ofMichigan, Princeton University, University of Southern California, andUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

TECHNICAL FIELD

The present invention generally relates to organic light emittingdevices (OLEDs), and organic compounds used in these devices.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules. In general, a small molecule has a well-definedchemical formula with a single molecular weight, whereas a polymer has achemical formula and a molecular weight that may vary from molecule tomolecule. As used herein, “organic” includes metal complexes ofhydrocarbyl and heteroatom-substituted hydrocarbyl ligands.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

OLED devices are generally (but not always) intended to emit lightthrough at least one of the electrodes, and one or more transparentelectrodes may be useful in an organic opto-electronic devices. Forexample, a transparent electrode material, such as indium tin oxide(ITO), may be used as the bottom electrode. A transparent top electrode,such as disclosed in U.S. Pat. Nos. 5,703,436 and 5,707,745, which areincorporated by reference in their entireties, may also be used. For adevice intended to emit light only through the bottom electrode, the topelectrode does not need to be transparent, and may be comprised of athick and reflective metal layer having a high electrical conductivity.Similarly, for a device intended to emit light only through the topelectrode, the bottom electrode may be opaque and/or reflective. Wherean electrode does not need to be transparent, using a thicker layer mayprovide better conductivity, and using a reflective electrode mayincrease the amount of light emitted through the other electrode, byreflecting light back towards the transparent electrode. Fullytransparent devices may also be fabricated, where both electrodes aretransparent. Side emitting OLEDs may also be fabricated, and one or bothelectrodes may be opaque or reflective in such devices.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. For example, for a devicehaving two electrodes, the bottom electrode is the electrode closest tothe substrate, and is generally the first electrode fabricated. Thebottom electrode has two surfaces, a bottom surface closest to thesubstrate, and a top surface further away from the substrate. Where afirst layer is described as “disposed over” a second layer, the firstlayer is disposed further away from substrate. There may be other layersbetween the first and second layer, unless it is specified that thefirst layer is “in physical contact with” the second layer. For example,a cathode may be described as “disposed over” an anode, even thoughthere are various organic layers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

The development of long-lived blue emissive phosphorescent dopants isrecognized as a key unfulfilled objective of current OLED research anddevelopment. While phosphorescent OLED devices with emission peaks inthe deep blue or near-UV have been demonstrated, the lifetimes ofblue-emissive devices exhibiting 100 nits initial luminance have been onthe order of several hundred hours (where “lifetime” refers to the timefor the luminance to decline to 50% of the initial level, at constantcurrent). For example, iridium(III) complexes of bidentate ligandsderived from N-methyl-2-phenylimidazoles can be used to prepare blueOLED devices, but very short lifetimes are observed with these dopants(about 250 hours at 100 nits initial luminescence).

Since most commercial applications are expected to require lifetimes inexcess of 10,000 hours at 200 nits initial luminescence, majorimprovements in blue phosphorescent OLED device lifetimes are sought.

SUMMARY

Pursuant to the aforementioned objective, we describe herein several newclasses of phosphorescent metal complexes and OLED devices comprisingcyclometallated imidazo[1,2-f]phenanthridine ordiimidazo[1,2-a:1′,2′-c]quinazoline ligands, or isoelectronic orbenzannulated analogs thereof, useful in the preparation of long-livedand efficient blue, green and red emissive OLED devices. Many of thesecomplexes have surprisingly narrow phosphorescent emission lineshapes,or triplet energies which are surprisingly high for such highlyconjugated molecules, or both. Density Functional Theory (DFT)calculations using the G98/B3lyp/cep-31g basis set suggest that many ofthe blue-emissive complexes of the current invention have relativelysmall singlet-triplet gaps, less than about 0.25 eV. Without wishing tobe bound by theory, the inventors believe that the 18 pi electron countand specific arrangement of fused rings is associated with the smallsinglet-triplet band gap and may have beneficial effects on the spectrallineshape and device lifetime. A small singlet-triplet gap may alsofacilitate the design of low voltage OLED devices and beneficiallyreduce the power consumption of OLED devices comprising such compounds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device having separate electrontransport, hole transport, and emissive layers, as well as other layers.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows IVL, spectral and lifetime data for a device comprisingcompound es1.

FIG. 4 shows IVL, spectral and lifetime data for a device comprisingcompound es6.

FIG. 5 shows IVL, spectral and lifetime data for a device comprisingcompound es8.

FIG. 6 shows IVL, spectral and lifetime data for a device comprisingcompound es9.

FIG. 7 shows IVL, spectral and lifetime data for a device comprisingcompound es13.

FIG. 8 shows IVL, spectral and lifetime data for a device comprisingcompound es14.

FIG. 9 shows IVL, spectral and lifetime data for a device comprisingcompound es16.

FIG. 10 shows IVL, spectral and lifetime data for a device comprisingcompound es17.

FIG. 11 shows IVL, and spectral data for compound a device comprisinges19.

FIG. 12 shows IVL, spectral and lifetime data for a device comprisingcompound es20.

FIG. 13 shows IVL, spectral and lifetime data for a device comprisingcompound es4.

FIG. 14 shows the emission spectrum of es101 in methylene chloridesolution.

FIG. 15 shows IVL, spectral and lifetime data for a device comprisingcompound es20 as the emitter and HILx as the hole injection layermaterial.

FIG. 16 shows IVL, spectral and lifetime data for a device comprisingcompound es20 as both emitter and hole injection layer material.

FIG. 17 shows the structure of the compound HILx

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence may be referred to asa “forbidden” transition because the transition requires a change inspin states, and quantum mechanics indicates that such a transition isnot favored. As a result, phosphorescence generally occurs in a timeframe exceeding at least 10 nanoseconds, and typically greater than 100nanoseconds. If the natural radiative lifetime of phosphorescence is toolong, triplets may decay by a non-radiative mechanism, such that nolight is emitted. Organic phosphorescence is also often observed inmolecules containing heteroatoms with unshared pairs of electrons atvery low temperatures. 2,2′-bipyridine is such a molecule. Non-radiativedecay mechanisms are typically temperature dependent, such that anorganic material that exhibits phosphorescence at liquid nitrogentemperatures typically does not exhibit phosphorescence at roomtemperature. But, as demonstrated by Baldo, this problem may beaddressed by selecting phosphorescent compounds that do phosphoresce atroom temperature. Representative emissive layers include doped orundoped phosphorescent organometallic materials such as disclosed inU.S. Pat. No. 6,303,238; 6,310,360; 6,830,828; and 6,835,469; U.S.Patent Application Publication No. 2002-0182441; and WO-02/074015.

Generally, the excitons in an OLED are believed to be created in a ratioof about 3:1, i.e., approximately 75% triplets and 25% singlets. See,Adachi et al., “Nearly 100% Internal Phosphorescent Efficiency In AnOrganic Light Emitting Device,” J. Appl. Phys., 90, 5048 (2001), whichis incorporated by reference in its entirety. In many cases, singletexcitons may readily transfer their energy to triplet excited states via“intersystem crossing.” whereas triplet excitons may not readilytransfer their energy to singlet excited states. As a result, 100%internal quantum efficiency is theoretically possible withphosphorescent OLEDs. In a fluorescent device, the energy of tripletexcitons is generally lost to radiationless decay processes that heat-upthe device, resulting in much lower internal quantum efficiencies. OLEDsutilizing phosphorescent materials that emit from triplet excited statesare disclosed, for example, in U.S. Pat. No. 6,303,238, which isincorporated by reference in its entirety.

Phosphorescence may be preceded by a transition from a triplet excitedstate to an intermediate non-triplet state from which the emissive decayoccurs. For example, organic molecules coordinated to lanthanideelements often phosphoresce from excited states localized on thelanthanide metal. However, such materials do not phosphoresce directlyfrom a triplet excited state but instead emit from an atomic excitedstate centered on the lanthanide metal ion. The europium diketonatecomplexes illustrate one group of these types of species.

Phosphorescence from triplets can be enhanced over fluorescence byconfining, preferably through bonding, the organic molecule in closeproximity to an atom of high atomic number. This phenomenon, called theheavy atom effect, is created by a mechanism known as spin-orbitcoupling. Such a phosphorescent transition may be observed from anexcited metal-to-ligand charge transfer (MLCT) state of anorganometallic molecule such as tris(2-phenylpyridine)iridium(III).While not wishing to be bound by theory, it is believed that the organicmetal to carbon bond in an organometallic complex is an especiallypreferred method of achieving the desired proximity of the organicmolecule to an atom of high atomic number. Specifically, in the contextof this application, the presence of the organic carbon-metal bond inthe organometallic complex may promote greater MLCT character, which canbe useful for the production of highly efficient devices.

As used herein, the term “triplet energy” refers to an energycorresponding to the highest energy feature discernable in thephosphorescence spectrum of a given material. The highest energy featureis not necessarily the peak having the greatest intensity in thephosphorescence spectrum, and could, for example, be a local maximum ofa clear shoulder on the high energy side of such a peak.

The term “organometallic” as used herein is as generally understood byone of ordinary skill in the art and as given, for example, in“Inorganic Chemistry” (2nd Edition) by Gary L. Miessler and Donald A.Tarr, Prentice Hall (1998). Thus, the term organometallic refers tocompounds which have an organic group bonded to a metal through acarbon-metal bond. This class does not include per se coordinationcompounds, which are substances having only donor bonds fromheteroatoms, such as metal complexes of amines, halides, pseudohalides(CN, etc.), and the like. In practice organometallic compounds maycomprise, in addition to one or more carbon-metal bonds to an organicspecies, one or more donor bonds from a heteroatom. The carbon-metalbond to an organic species refers to a direct bond between a metal and acarbon atom of an organic group, such as phenyl, alkyl, alkenyl, etc.,but does not refer to a metal bond to an “inorganic carbon,” such as thecarbon of CN or CO.

FIG. 1 shows an organic light emitting. The figures are not necessarilydrawn to scale. Device 10) may include a substrate 110, an anode 115, ahole injection layer 120, a hole transport layer 125, an electronblocking layer 130, an emissive layer 135, a hole blocking layer 140, anelectron transport layer 145, an electron injection layer 150, aprotective layer 155, and a cathode 160. Cathode 160 is a compoundcathode having a first conductive layer 162 and a second conductivelayer 164. Device 100 may be fabricated by depositing the layersdescribed, in order.

Substrate 110 may be any suitable substrate that provides desiredstructural properties. Substrate 110 may be flexible or rigid. Substrate110 may be transparent, translucent or opaque. Plastic and glass areexamples of preferred rigid substrate materials. Plastic and metal foilsare examples of preferred flexible substrate materials. Substrate 110may be a semiconductor material in order to facilitate the fabricationof circuitry. For example, substrate 110 may be a silicon wafer uponwhich circuits are fabricated, capable of controlling OLEDs subsequentlydeposited on the substrate. Other substrates may be used. The materialand thickness of substrate 110 may be chosen to obtain desiredstructural and optical properties.

Anode 115 may be any suitable anode that is sufficiently conductive totransport holes to the organic layers. The material of anode 115preferably has a work function higher than about 4 eV (a “high workfunction material”). Preferred anode materials include conductive metaloxides, such as indium tin oxide (ITO) and indium zinc oxide (IZO),aluminum zinc oxide (AlZnO), and metals. Anode 115 (and substrate 110)may be sufficiently transparent to create a bottom-emitting device. Apreferred transparent substrate and anode combination is commerciallyavailable ITO (anode) deposited on glass or plastic (substrate). Aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. Nos. 5,844,363 and 6,602,540 B2, which are incorporated byreference in their entireties. Anode 115 may be opaque and/orreflective. A reflective anode 115 may be preferred for sometop-emitting devices, to increase the amount of light emitted from thetop of the device. The material and thickness of anode 115 may be chosento obtain desired conductive and optical properties. Where anode 115 istransparent, there may be a range of thickness for a particular materialthat is thick enough to provide the desired conductivity, yet thinenough to provide the desired degree of transparency. Other anodematerials and structures may be used.

Hole transport layer 125 may include a material capable of transportingholes.

Hole transport layer 130 may be intrinsic (undoped), or doped. Dopingmay be used to enhance conductivity. α-NPD and TPD are examples ofintrinsic hole transport layers. An example of a p-doped hole transportlayer is m-MTDATA doped with F₄-TCNQ at a molar ratio of 50:1, asdisclosed in United States Patent Application Publication No.2003-0230980 to Forrest et al., which is incorporated by reference inits entirety. Other hole transport layers may be used.

Emissive layer 135 may include an organic material capable of emittinglight when a current is passed between anode 115 and cathode 160.Preferably, emissive layer 135 contains a phosphorescent emissivematerial, although fluorescent emissive materials may also be used.Phosphorescent materials are preferred because of the higher luminescentefficiencies associated with such materials. Emissive layer 135 may alsocomprise a host material capable of transporting electrons and/or holes,doped with an emissive material that may trap electrons, holes, and/orexcitons, such that excitons relax from the emissive material via aphotoemissive mechanism. Emissive layer 135 may comprise a singlematerial that combines transport and emissive properties. Whether theemissive material is a dopant or a major constituent, emissive layer 135may comprise other materials, such as dopants that tune the emission ofthe emissive material. Emissive layer 135 may include a plurality ofemissive materials capable of, in combination, emitting a desiredspectrum of light. Examples of phosphorescent emissive materials includeIr(ppy)₃. Examples of fluorescent emissive materials include DCM andDMQA. Examples of host materials include Alq₃. CBP and mCP. Examples ofemissive and host materials are disclosed in U.S. Pat. No. 6,303,238 toThompson et al., which is incorporated by reference in its entirety.Emissive material may be included in emissive layer 135 in a number ofways. For example, an emissive small molecule may be incorporated into apolymer. This may be accomplished by several ways: by doping the smallmolecule into the polymer either as a separate and distinct molecularspecies; or by incorporating the small molecule into the backbone of thepolymer, so as to form a co-polymer; or by bonding the small molecule asa pendant group on the polymer. Other emissive layer materials andstructures may be used. For example, a small molecule emissive materialmay be present as the core of a dendrimer.

Many useful emissive materials include one or more ligands bound to ametal center. A ligand may be referred to as “photoactive” if itcontributes directly to the photoactive properties of an organometallicemissive material. A “photoactive” ligand may provide, in conjunctionwith a metal, the energy levels from which and to which an electronmoves when a photon is emitted. Other ligands may be referred to as“ancillary.” Ancillary ligands may modify the photoactive properties ofthe molecule, for example by shifting the energy levels of a photoactiveligand, but ancillary ligands do not directly provide the energy levelsinvolved in light emission. A ligand that is photoactive in one moleculemay be ancillary in another. These definitions of photoactive andancillary are intended as non-limiting theories.

Electron transport layer 145 may include a material capable oftransporting electrons. Electron transport layer 145 may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity. Alq₃ isan example of an intrinsic electron transport layer. An example of ann-doped electron transport layer is BPhen doped with Li at a molar ratioof 1:1, as disclosed in United States Patent Application Publication No.2003-0230980 to Forrest et al., which is incorporated by reference inits entirety. Other electron transport layers may be used.

The charge carrying component of the electron transport layer may beselected such that electrons can be efficiently injected from thecathode into the LUMO (Lowest Unoccupied Molecular Orbital) energy levelof the electron transport layer. The “charge carrying component” is thematerial responsible for the LUMO energy level that actually transportselectrons. This component may be the base material, or it may be adopant. The LUMO energy level of an organic material may be generallycharacterized by the electron affinity of that material and the relativeelectron injection efficiency of a cathode may be generallycharacterized in terms of the work function of the cathode material.This means that the preferred properties of an electron transport layerand the adjacent cathode may be specified in terms of the electronaffinity of the charge carrying component of the ETL and the workfunction of the cathode material. In particular, so as to achieve highelectron injection efficiency, the work function of the cathode materialis preferably not greater than the electron affinity of the chargecarrying component of the electron transport layer by more than about0.75 eV, more preferably, by not more than about 0.5 eV. Similarconsiderations apply to any layer into which electrons are beinginjected.

Cathode 160 may be any suitable material or combination of materialsknown to the art, such that cathode 160 is capable of conductingelectrons and injecting them into the organic layers of device 100.Cathode 160 may be transparent or opaque, and may be reflective. Metalsand metal oxides are examples of suitable cathode materials. Cathode 160may be a single layer, or may have a compound structure. FIG. 1 shows acompound cathode 160 having a thin metal layer 162 and a thickerconductive metal oxide layer 164. In a compound cathode, preferredmaterials for the thicker layer 164 include ITO. IZO, and othermaterials known to the art. U.S. Pat. Nos. 5,703,436, 5,707,745,6,548,956 B2 and 6,576,134 B2, which are incorporated by reference intheir entireties, disclose examples of cathodes including compoundcathodes having a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thepart of cathode 160 that is in contact with the underlying organiclayer, whether it is a single layer cathode 160, the thin metal layer162 of a compound cathode, or some other part, is preferably made of amaterial having a work function lower than about 4 eV (a “low workfunction material”). Other cathode materials and structures may be used.

Blocking layers may be used to reduce the number of charge carriers(electrons or holes) and/or excitons that leave the emissive layer. Anelectron blocking layer 130 may be disposed between emissive layer 135and the hole transport layer 125, to block electrons from leavingemissive layer 135 in the direction of hole transport layer 125.Similarly, a hole blocking layer 140 may be disposed between emissivelayer 135 and electron transport layer 145, to block holes from leavingemissive layer 135 in the direction of electron transport layer 145.Blocking layers may also be used to block excitons from diffusing out ofthe emissive layer. The theory and use of blocking layers is describedin more detail in U.S. Pat. No. 6,097,147 and United States PatentApplication Publication No. 2003-0230980 to Forrest et al., which areincorporated by reference in their entireties.

As used herein, and as would be understood by one skilled in the art,the term “blocking layer” means that the layer provides a barrier thatsignificantly inhibits transport of charge carriers and/or excitonsthrough the device, without suggesting that the layer necessarilycompletely blocks the charge carriers and/or excitons. The presence ofsuch a blocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

Generally, injection layers are comprised of a material that may improvethe injection of charge carriers from one layer, such as an electrode oran organic layer, into an adjacent organic layer. Injection layers mayalso perform a charge transport function. In device 100, hole injectionlayer 120 may be any layer that improves the injection of holes fromanode 115 into hole transport layer 125. CuPc is an example of amaterial that may be used as a hole injection layer from an ITO anode115, and other anodes. In device 100, electron injection layer 150 maybe any layer that improves the injection of electrons into electrontransport layer 145. LiF/Al is an example of a material that may be usedas an electron injection layer into an electron transport layer from anadjacent layer. Other materials or combinations of materials may be usedfor injection layers. Depending upon the configuration of a particulardevice, injection layers may be disposed at locations different thanthose shown in device 100. More examples of injection layers areprovided in U.S. patent application Ser. No. 09/931,948 to Lu et al.,which is incorporated by reference in its entirety. A hole injectionlayer may comprise a solution deposited material, such as a spin-coatedpolymer, e.g., PEDOT:PSS, or it may be a vapor deposited small moleculematerial, e.g., CuPc or MTDATA.

A hole injection layer (HIL) may planarize or wet the anode surface soas to provide efficient hole injection from the anode into the holeinjecting material. A hole injection layer may also have a chargecarrying component having HOMO (Highest Occupied Molecular Orbital)energy levels that favorably match up, as defined by theirherein-described relative ionization potential (IP) energies, with theadjacent anode layer on one side of the HIL and the hole transportinglayer on the opposite side of the HIL. The “charge carrying component”is the material responsible for the HOMO energy level that actuallytransports holes. This component may be the base material of the HIL, orit may be a dopant. Using a doped HIL allows the dopant to be selectedfor its electrical properties, and the host to be selected formorphological properties such as wetting, flexibility, toughness, etc.Preferred properties for the HIL material are such that holes can beefficiently injected from the anode into the HIL material. Inparticular, the charge carrying component of the HIL preferably has anIP not more than about 0.7 eV greater that the IP of the anode material.More preferably, the charge carrying component has an IP not more thanabout 0.5 eV greater than the anode material. Similar considerationsapply to any layer into which holes are being injected. HIL materialsare further distinguished from conventional hole transporting materialsthat are typically used in the hole transporting layer of an OLED inthat such HIL materials may have a hole conductivity that issubstantially less than the hole conductivity of conventional holetransporting materials. The thickness of the HIL of the presentinvention may be thick enough to help planarize or wet the surface ofthe anode layer. For example, an HIL thickness of as little as 10 nm maybe acceptable for a very smooth anode surface. However, since anodesurfaces tend to be very rough, a thickness for the HIL of up to 50 nmmay be desired in some cases.

A protective layer may be used to protect underlying layers duringsubsequent fabrication processes. For example, the processes used tofabricate metal or metal oxide top electrodes may damage organic layers,and a protective layer may be used to reduce or eliminate such damage.In device 100, protective layer 155 may reduce damage to underlyingorganic layers during the fabrication of cathode 160. Preferably, aprotective layer has a high carrier mobility for the type of carrierthat it transports (electrons in device 100), such that it does notsignificantly increase the operating voltage of device 100. CuPc, BCP,and various metal phthalocyanines are examples of materials that may beused in protective layers. Other materials or combinations of materialsmay be used. The thickness of protective layer 155 is preferably thickenough that there is little or no damage to underlying layers due tofabrication processes that occur after organic protective layer 160 isdeposited, yet not so thick as to significantly increase the operatingvoltage of device 100. Protective layer 155 may be doped to increase itsconductivity. For example, a CuPc or BCP protective layer 160 may bedoped with Li. A more detailed description of protective layers may befound in U.S. patent application Ser. No. 09/931,948 to Lu et al., whichis incorporated by reference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,an cathode 215, an emissive layer 220, a hole transport layer 225, andan anode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190, Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink-jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

The molecules disclosed herein may be substituted in a number ofdifferent ways without departing from the scope of the invention. Forexample, substituents may be added to a compound having three bidentateligands, such that after the substituents are added, one or more of thebidentate ligands are linked together to form, for example, atetradentate or hexadentate ligand. Other such linkages may be formed.It is believed that this type of linking may increase stability relativeto a similar compound without linking, due to what is generallyunderstood in the art as a “chelating effect.”

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, televisions, billboards, lights forinterior or exterior illumination and/or signaling, heads up displays,fully transparent displays, flexible displays, laser printers,telephones, cell phones, personal digital assistants (PDAs), laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays,vehicles, a large area wall, theater or stadium screen, or a sign.Various control mechanisms may be used to control devices fabricated inaccordance with the present invention, including passive matrix andactive matrix. Many of the devices are intended for use in a temperaturerange comfortable to humans, such as 18 degrees C. to 30 degrees C., andmore preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The term “aryl” refers to an aromatic carbocyclic monoradical. Unlessotherwise specified, the aromatic carbocyclic monoradical may besubstituted or unsubstituted. The substituents can be F, hydrocarbyl,heteroatom-substituted hydrocarbyl, cyano, and the like.

A “hydrocarbyl” group means a monovalent or divalent, linear, branchedor cyclic group which contains only carbon and hydrogen atoms. Examplesof monovalent hydrocarbyls include the following: C₁-C₂₀ alkyl; C₁-C₂₀alkyl substituted with one or more groups selected from C₁-C₂₀ alkyl.C₃-C₈ cycloalkyl, and aryl; C₃-C₈ cycloalkyl; C₃-C₈ cycloalkylsubstituted with one or more groups selected from C₁-C₂₀ alkyl, C₃-C₈cycloalkyl, and aryl; C₆-C₁₈ aryl; and C₆-C₁₈ aryl substituted with oneor more groups selected from C₁-C₂₀ alkyl, C₃-C₈ cycloalkyl, and aryl.Examples of divalent (bridging) hydrocarbyls include: —CH₂—; —CH₂CH₂—;—CH₂CH₂CH₂—; and 1,2-phenylene.

A “heteroatom” refers to an atom other than carbon or hydrogen. Examplesof heteroatoms include oxygen, nitrogen, phosphorus, sulfur, selenium,arsenic, chlorine, bromine, silicon, and fluorine.

A “heteroaryl” refers to a heterocyclic monoradical that is aromatic.Unless otherwise specified, the aromatic heterocyclic monoradical may besubstituted or unsubstituted. The substituents can be F, hydrocarbyl,heteroatom-substituted hydrocarbyl, cyano, and the like. Examples ofheteroaryls include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, furyl, thienyl,indenyl, imidazolyl, oxazolyl, isoxazolyl, carbazolyl, thiazolyl,pyrimidinyl, pyridyl, pyridazinyl, pyrazinyl, benzothienyl, and thelike, and substituted derivatives thereof.

By “ortho positions,” we mean the positions on the aryl or heteroarylgroup which are adjacent to the point of attachment of the second ringto the first ring. In the case of a six-membered ring aryl groupattached via the 1-position, such as 2,6-dimethylphenyl, the 2- and6-positions are the ortho positions. In the case of a 5-membered ringheteroaryl group attached via the 1-position, such as2,5-diphenylpyrrol-1-yl, the 2- and 5-positions are the ortho positions.In the context of this invention, ring fusion at a carbon adjacent tothe point of attachment, as in 2,3,4,5,7,8,9,10-ocathydroanthracen-1-yl,is considered to be a type of ortho substitution.

Thus, in a first aspect, this invention relates to a compound comprisinga phosphorescent metal complex comprising a monoanionic, bidentateligand selected from Set 1, wherein the metal is selected from the groupconsisting of the non-radioactive metals with atomic numbers greaterthan 40, and wherein the bidentate ligand may be linked with otherligands to comprise a tridentate, tetradentate, pentadentate orhexadentate ligand:

wherein:

E^(1a-q) are selected from the group consisting of C and N andcollectively comprise an 18 pi-electron system; provided that E^(1a) andE^(1p) are different; and

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a first preferred embodiment of this first aspect, the metal isselected from the group consisting of Re, Ru, Os, Rh, Ir, Pd, Pt, andAu, and the bidentate ligand is selected from Set 2; even morepreferably, the bidentate ligand is of formula gs1-1 in Set 2;

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b).BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring.

In a second preferred embodiment, the metal is Ir or Pt and thebidentate ligand is selected from Set 2. In a third preferredembodiment, the metal complex is a homoleptic Ir complex of a ligandselected from Set 2. In a fourth preferred embodiment, the metal complexis a heteroleptic Ir complex comprising two bidentate ligands selectedfrom Set 2 and a third monoanionic bidentate ligand, preferablyacetylacetonate or a substituted acetylacetonate. In a fifth preferredembodiment, the metal is selected from the group consisting of Re, Ru,Os, Rh, Ir, Pd, Pt, and Au, and at least one of R^(1a-i) is a2,6-di-substituted aryl group. In a sixth preferred embodiment, themetal is selected from the group consisting of Ir and Pt, the ligand isof formula gs1-1, and R^(1b) is a 2,6-di-substituted aryl group,preferably selected from the group consisting of 2,6-dimethylphenyl;2,4,6-trimethylphenyl; 2,6-di-isopropylphenyl; 2,4,6-triisopropylphenyl;2,6-di-isopropyl-4-phenylphenyl; 2,6-dimethyl-4-phenylphenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl; 2,6-diphenylphenyl;2,6-diphenyl-4-isopropylphenyl; 2,4,6-triphenylphenyl;2,6-di-isopropyl-4-(4-isopropylphenyl);2,6-di-isopropyl-4-(3,5-dimethylphenyl)phenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl;2,6-di-isopropyl-4-(pyridine-4-yl)phenyl; and2,6-di-(3,5-dimethylphenyl)phenyl.

In a second aspect, this invention relates to a compound selected fromSet 3, wherein acac is acetylacetonate;

In a third aspect, this invention relates to an OLED device comprisingany of the compounds of the first or second aspects.

In a fourth aspect, this invention relates to a compound comprising aphosphorescent metal complex comprising a monoanionic, bidentate ligandselected from Set 4, wherein the metal is selected from the groupconsisting of the non-radioactive metals with atomic numbers greaterthan 40, and wherein the bidentate ligand may be linked with otherligands to comprise a tridentate, tetradentate, pentadentate orhexadentate ligand:

wherein:

E^(1a-q) are each, independently, selected from the group consisting ofC and N, and collectively comprise an 18 pi-electron system; providedthat E^(1a) and E^(1p) are different; and

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a first preferred embodiment of this fourth aspect, the bidentateligand is selected from Set 5:

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2C), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a ring.

In a second preferred embodiment of the fourth aspect, the bidentateligand is selected from Set 6;

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2C), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a ring.

In a third preferred embodiment of the fourth aspect, the bidentateligand is substituted by one or more 2,6-disubstituted aryl orheteroaryl groups, preferably selected from the group consisting of2,6-dimethylphenyl; 2,4,6-trimethylphenyl; 2,6-di-isopropylphenyl;2,4,6-triisopropylphenyl; 2,6-di-isopropyl-4-phenylphenyl;2,6-dimethyl-4-phenylphenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl; 2,6-diphenylphenyl;2,6-diphenyl-4-isopropylphenyl; 2,4,6-triphenylphenyl;2,6-di-isopropyl-4-(4-isopropylphenyl);2,6-di-isopropyl-4-(3,5-dimethylphenyl)phenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl;2,6-di-isopropyl-4-(pyridine-4-yl)phenyl; and2,6-di-(3,5-dimethylphenyl)phenyl.

In a fourth preferred embodiment of the fourth aspect, the metal isselected from the group consisting of Re, Ru, Os, Rh, Ir, Pd, Pt, andAu, and is more preferably selected from the group consisting of Os, Irand Pt, and is most preferably Ir.

In a fifth aspect, this invention relates to an OLED device comprising acompound of the fourth aspect.

In a sixth aspect, this invention relates to a compound corresponding toa ligand of the fourth aspect, wherein the metal has been replaced by H.

In a seventh aspect, this invention relates to a compound comprising aphosphorescent metal complex comprising a monoanionic, bidentate ligandselected from Set 7, wherein the metal is selected from the groupconsisting of the non-radioactive metals with atomic numbers greaterthan 40, and wherein the bidentate ligand comprises a carbene donor andmay be linked with other ligands to comprise a tridentate, tetradentate,pentadentate or hexadentate ligand;

wherein:

E^(1a-q) are selected from the group consisting of C and N andcollectively comprise an 18 pi-electron system; provided that E^(1a) andE^(1p) are both carbon; and

R^(1a-i) are each, independently. H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a first preferred embodiment of this seventh aspect, the compound isselected from Set 8;

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In an eighth aspect, this invention relates to an OLED device comprisinga compound of the seventh aspect.

In a ninth aspect, this invention relates to a compound comprising aphosphorescent metal complex comprising a monoanionic, bidentate ligandselected from Set 9, wherein the metal is selected from the groupconsisting of the non-radioactive metals with atomic numbers greaterthan 40, and wherein the bidentate ligand comprises a carbene donor andmay be linked with other ligands to comprise a tridentate, tetradentate,pentadentate or hexadentate ligand;

wherein:

E^(1a-q) are selected from the group consisting of C and N andcollectively comprise an 18 pi-electron system; provided that E^(1a) andE^(1p) are both carbon; and

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a first preferred embodiment of this ninth aspect, the compound isselected from Set 10;

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a tenth aspect, this invention relates to an OLED device comprising acompound of the ninth aspect.

In an eleventh aspect, this invention relates to a compound comprising aphosphorescent metal complex comprising a monoanionic, bidentate ligandselected from Set 11, wherein the metal is selected from the groupconsisting of the non-radioactive metals with atomic numbers greaterthan 40, and wherein the bidentate ligand may be linked with otherligands to comprise a tridentate, tetradentate, pentadentate orhexadentate ligand:

wherein:

R^(1a-i) are each, independently, H, hydrocarbyl, heteroatom substitutedhydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring; provided that R^(1a-i) isother than H when attached to N.

In a twelfth aspect, this invention relates to an OLED device comprisinga compound of the eleventh aspect.

In a thirteenth aspect, this invention relates to a compoundcorresponding to a ligand of the eleventh aspect, wherein the metal hasbeen replaced by H.

In a fourteenth aspect, this invention relates to a compound comprisinga metal complex selected from Table 1.

In a fifteenth aspect, this invention relates to an OLED devicecomprising a compound of the fourteenth aspect.

Table 1 below provides Density Function Theory (DFT) calculations usingthe G98/B3lyp/cep-31g basis set to obtain estimates of the HOMO, LUMO,gap, dipole, S1, and TI for various compounds of the present invention.

TABLE 1 Cal. Cal. Cal. Cal. Cal. Cal. HOMO LUMO Gap Dipole S1 T1 EntryCompounds (ev) (ev) (ev) (Debye) (nm) (nm) 1

−4.73 −1.17 3.57 4.72 446 475 2

−4.99 −1.33 3.65 0.21 434 470 3

−5.11 −1.21 3.90 3.44 394 477 4

−4.88 −1.42 3.46 3.06 465 493 5

−5.17 −1.47 3.69 11.40 427 467 6

−4.83 −0.93 3.90 8.28 425 490 7

−4.52 −0.77 3.75 11.91 396 493 8

−4.96 −1.04 3.92 18.02 401 485 9

−4.92 −1.43 3.49 18.06 414 488 10

−5.15 −1.65 3.49 11.79 444 479 11

−4.38 −0.81 3.57 2.90 447 471 12

−4.93 −1.62 3.31 14.71 455 492 13

−4.51 −0.99 3.52 5.76 459 495 14

−5.45 −1.98 3.47 4.41 454 478 15

−4.55 −0.94 3.61 8.96 442 478 16

−4.58 −0.96 3.62 4.96 443 476 17

−4.61 −1.09 3.52 6.18 450 480 18

−4.90 −1.54 3.36 4.74 476 552 19

−4.94 −1.74 3.19 2.12 485 613 20

−5.13 −2.01 3.12 1.52 511 540 21

−4.88 −1.30 3.58 3.14 450 479 22

−4.53 −1.01 3.52 8.65 454 478 23

−4.67 −1.06 3.60 8.96 447 481 24

−4.82 −1.36 3.46 3.33 454 517 25

−5.28 −1.60 3.68 10.11 435 473 26

−5.21 −1.64 3.57 10.21 439 510 27

−5.25 −1.61 3.64 9.35 440 476 28

−5.13 −2.45 2.68 2.31 590 674 29

−5.10 −1.37 3.74 16.13 430 474 30

−5.25 −1.61 3.63 10.28 438 481 31

−4.66 −1.17 3.49 4.35 448 479 32

−4.50 −0.91 3.59 7.98 444 480 33

−4.33 −0.67 3.66 8.45 433 474 34

−4.38 −0.80 3.57 2.77 447 471 35

−4.64 −1.31 3.33 7.04 479 486 36

−4.88 −1.47 3.41 1.43 456 483 37

−5.02 −1.90 3.12 2.82 471 486 38

−4.79 −1.32 3.47 0.10 456 484 39

−4.85 −1.40 3.45 3.14 458 487 40

−4.66 −1.11 3.55 5.48 445 478 41

−4.67 −1.12 3.55 5.76 448 477 42

−4.54 −1.08 3.46 7.01 460 484 43

−4.52 −1.05 3.47 2.72 462 483 44

−5.11 −1.62 3.49 10.59 453 478 45

−4.75 −1.45 3.30 5.02 487 518 46

−5.08 −2.18 2.90 13.63 531 623 47

−5.22 −1.76 3.46 5.70 467 485 48

−4.87 −1.37 3.50 3.13 468 481 49

−4.56 −0.97 3.85 5.02 442 474 50

−4.57 −0.97 3.60 5.03 441 477 51

−4.57 −1.10 3.47 4.94 447 480 52

−4.51 −1.06 3.45 4.36 447 479 53

−4.45 −1.01 3.44 4.77 441 478 54

−4.58 −0.98 3.60 4.92 442 476 55

−4.65 −1.04 3.60 5.43 442 476 56

−4.52 −0.92 3.60 6.23 442 476 57

−4.45 −0.85 3.60 7.72 442 476 58

−4.49 −0.87 3.62 5.45 438 474 59

−5.27 −1.91 3.36 2.99 478 501 60

−5.75 −2.39 3.37 4.27 476 507 61

−5.22 −1.46 3.77 0.08 427 463 62

−5.68 −2.05 3.64 4.12 441 467 63

−5.88 −2.40 3.48 3.83 460 472 64

−4.74 −1.65 3.08 9.02 469 484 65

−5.37 −1.69 3.68 8.08 434 472 66

−5.32 −1.33 4.00 0.25 389 476 67

−4.24 −0.65 3.60 3.14 449 480 68

−4.28 −0.71 3.57 3.23 454 479 69

−4.82 −1.20 3.62 1.03 440 475 70

−4.95 −1.36 3.59 0.28 441 476 71

−4.65 −1.18 3.47 5.66 442 476 72

−4.44 −0.82 3.62 5.50 439 479 73

−5.19 −1.79 3.40 0.50 468 483 74

−5.16 −1.64 3.51 7.01 452 479 75

−4.49 −0.80 3.69 6.62 434 475 76

−5.01 −0.97 4.04 3.07 375 446 77

−5.46 −1.44 4.01 2.34 377 448 78

−5.22 −1.24 3.97 8.24 382 451 79

−5.10 −0.99 4.11 10.38 400 465 80

−5.84 −1.96 3.88 0.91 409 529 81

−5.30 −1.48 3.82 1.26 412 542 82

−5.19 −1.18 4.01 2.09 377 449 83

−5.33 −1.31 4.02 2.45 376 448 84

−5.34 −1.53 3.82 1.53 403 463 85

−5.40 −1.70 3.70 1.70 419 480 86

−5.39 −1.52 3.87 3.36 428 461 87

−5.31 −1.61 3.70 7.43 423 473 88

−4.85 −1.17 3.68 2.60 427 485 89

−4.88 −1.33 3.55 2.32 442 496 90

−5.46 −1.66 3.80 0.78 412 494 91

−5.28 −1.57 3.71 2.81 419 479 92

−5.24 −1.53 3.71 1.74 421 479 93

−5.19 −1.51 3.68 2.80 432 483 94

−6.19 −2.54 3.66 9.25 429 472 95

−5.86 −2.11 3.74 10.90 426 460 96

−5.06 −1.11 3.95 2.69 381 456 97

−5.22 −1.45 3.76 0.68 397 473 98

−4.91 −0.96 3.95 2.51 383 460 99

— — — — — — 100

−5.13 −1.39 3.74 2.52 422 472

EXAMPLES

Unless otherwise indicated, the preparation and purification of thephosphorescent metal complexes described herein were carried out in dimroom light or with yellow filters over the lights or using aluminumfoil-wrapped glassware so as to minimize photo-oxidation of the metalcomplexes. The complexes vary considerably in their sensitivity. Forexample, some complexes such as es20 require only modest care and somecomplexes such as es1 are quite prone to light-induced decomposition inair and in certain halogenated solvents. Unless otherwise specified, thefac-isomers were isolated.

Example 1 Preparation of es1

Step 1

Phenanthridinone (5.0 grams, 0.027 mole) was added to a reaction flaskcontaining phosphorus pentachloride (6.1 grams, 0.29 mole) and 50 mL ofphosphoryl chloride. The reaction mixture was refluxed for 1 hour,cooled to room temperature and diluted with toluene. The excessphosphoryl chloride and toluene were removed on a rotary evaporator. Theresidue was dissolved into ethyl acetate and washed with distilled waterfollowed by brine. The solvent layer was dried over magnesium sulfate,filtered and concentrated to give p12-i1 (5.5 grams, 96%) as anoff-white solid. The product was confirmed by Mass Spectrometry and ¹HNMR and used directly in the next step.

Step 2

Compound p12-i1 from Step 1 (5.5 grams, 0.026 mole) was added to areaction flask containing aminoacetaldehyde dimethylacetal (6.8 grams,0.0646 mole) dissolved into 200 mL diglyme, heated to reflux and stirredunder a nitrogen atmosphere. After 72 hours the reaction was complete asdetermined by TLC. The reaction mixture was cooled to room temperatureand the excess solvent removed by distillation. The residue was taken upinto methylene chloride and the insolubles were removed by vacuumfiltration. The solvent was dried over magnesium sulfate filtered andconcentrated. The crude product was purified by silica gelchromatography using 80% ethyl acetate and 20% methylene chloride as theeluents. The purified product was collected, washed with hexanes, anddried to give p12-H (2.6 grams, 46% yield) as an off-white solid.

Step 3

Compound p12-H (0.67 g, 3.1 mmol) from Step 2 above and iridium(III)acetylacetonate (0.38 gram, 0.77 mmol) were heated to 250° C. overnightunder a nitrogen atmosphere. After the reaction was cooled, the residuewas taken up into a 1:1 mixture of ethyl acetate and methylene chloride,filtered and purified by a first silica gel chromatography using 1:1ethyl acetate:hexanes followed by a second silica gel column using 1:1chloroform:hexanes to afford es1 (0.15 gram, 23% yield) as a beigesolid. The high energy peak for the phosphorescence in dichloromethanesolution was centered at 458 nm with CIE coordinates 0.18, 0.27.

Example 2 General Procedure A for Imidazophenanthridine Ligand Syntheses

To a 1 L round flask was added 2-iodo-4,5-dimethylanaline (24.7 g, 100mmol), 2-cyanophenylboronic acid, pinacol ester (27.5 g, 120 mmol),dichlorobis(triphenylphosphine) palladium(II) (3.51 g, 5 mmol),potassium phosphate tribasic monohydrate (46.0 g, 200 mmol), and 400 mLof toluene. The reaction was heated to reflux and stirred under anitrogen atmosphere for 4 hours. After cooling, the precipitate formedwas filtered and washed with toluene, hexanes and water. Yield was 14 g.

To a 1 L round flask was added the above intermediate,chloroacetaldehyde (50% wt. in water, 15.7 g, 100 mmol), sodiumcarbonate (15.9 g, 150 mmol), and 300 mL of 2-propanol. The mixture washeated to reflux for 2 hours. The solvents were removed and the residuewas extracted with CH₂Cl₂ and further purified by a silica gel column.Yield was 13 g.

Example 3 General Procedure for Tris(Bidentate Ligand)Iridium ComplexSynthesis

The following procedure was conducted in dim room light or using yellowfilters over the light sources or with aluminum foil-w rapped glasswareto minimize photo-oxidation of the metal complex. A 50 mL Schlenk tubeflask was charged with 6,7-dimethylimidazo[1,2-f]phenanthridine (1.68 g,6.8 mmol) and tris(acetylacetonate)iridium(III) (0.59 g, 1.4 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 48 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive es12 (0.30 g). The structure and purity was confirmed by ¹H NMRanalysis. λ_(max) emission=456, 486 nm (in CH₂Cl₂ solution at roomtemperature); CIE=(0.18, 0.23).

Example 4 Preparation of es3

A 50 mL Schlenk tube flask was charged with8b,13-diaza-indeno[1,2-f]phenanthrene (3.49 g, 13 mmol) andtris(acetylacetonate)iridium(III) (1.27 g, 2.6 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees3 (1.4 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=492, 524 nm (CH₂Cl₂ solution at room temperature), CIE=(0.23,0.51).

Example 5 Preparation of es4

A 50 mL Schlenk tube flask was charged with10-isopropyl-8b,13-diaza-indeno[1,2-f]phenanthrene (6.07 g, 19.6 mmol)and tris(acetylacetonate)iridium(III) (1.91 g, 3.92 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees4 (0.7 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=496 nm (CH₂Cl₂ solution at room temperature), CIE=(0.26, 0.57).

Example 6 Preparation of es7

Step 1: Synthesis of 4-bromo-6-aminophenanthridine

A three neck 1 L round bottom flask was charged with 2,6-dibromoaniline(143.51 g, 0.57 mole), 2-cyanophenylbornic acid trimethylene ester(34.35 g, 0.19 mole), K₃PO₄. H₂O (43.89 g, 0.1906 mole), PdCl₂(PPh₃)₂(6.67 g, 9.5 mmole) and anhydrous toluene (700 ml). The reaction mixturewas heated to 100° C. under nitrogen for 6 hrs. The reaction mixture wasthen concentrated to dryness and subjected to column chromatography toobtain the title compound (19.11 g, 36.7%).

Step 2: Synthesis of 5-bromo-imidazo[1,2-f]phenanthridine

To a mixture of 4-bromo-6-aminophenanthridine (19.11 g, 69.91 mmole),sodium bicarbonate (12.3 g, 146 mmole) in 2-propanol (200 ml) was addedchloroacetaldehyde (50% aqueous soln, 17.35 g). After the reactionmixture was heated at 75° C. for 5 hrs., the solvent was removed. Theresidue was redissolved in methylene chloride and washed with water. Theorganic fractions were combined, dried over sodium sulfate, filtered,and concentrated in vacuo. The crude mixture was purified bychromagraphy on silica gel using hexane-ethyl acetate (80/20) to obtainthe title compound (13 g, 62%).

Step 3: Synthesis of 5-(4-isopropylphenyl)-imidazo[1,2-f]phenanthridine

A three neck 1 L round bottom flask was charged with5-bromo-imidazo[1,2-f]phenanthridine (4.55 g, 15.31 mmole),4-isopropylphenylbornic acid (3.59 g, 21.89 mmole), potassium carbonate(2N aqueous soln., 27 ml), Pd(OAc)₂ (223 mg, 0.99 mmole),triphenylphosphine(1.044 g, 3.98 mmole) and 100 ml of1,2-dimethoxyethane. The reaction mixture was heated to 80° C. undernitrogen for 17 hrs. The reaction mixture was diluted with methylenechloride and washed by brine. The organic fractions were combined, driedover sodium sulfate, filtered, and concentrated in vacuo. The crudemixture was purified by chromagraphy on silica gel using hexane/ethylacetate (80/20) to obtain pure5-(4-isopropylphenyl)-imidazo[1,2-f]phenanthridine (4 g, 77%).

Step 4: Complexation

A 50 mL Schlenk tube flask was charged with5-(4-isopropylphenyl)imidazo[1,2-f]phenanthridine (2.94 g, 8.74 mmol)and tris(acetylacetonate)iridium(III) (0.86 g, 1.75 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees7 (0.7 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=496 nm (CH₂Cl₂ solution at room temperature), CIE=(0.26, 0.57).

Example 7 Preparation of es10

Step 1: Ligand Synthesis

To a 500 mL round flask was added 7-chloroimidazo[1,2-f]phenanthridine(3.8 g, 15 mmol, prepared from the general procedure A),4-isopropylphenylboronic acid (3.7 g, 23 mmol), palladium(II) acetate(0.084 g, 0.38 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(S-Phos, 0.31 g, 0.75 mmol), potassium phosphate tribasic monohydrate(6.9 g, 30 mmol), and 200 mL of toluene. The reaction was heated toreflux and stirred under a nitrogen atmosphere for 12 hours. Aftercooling, the mixture was purified by a silica gel column. Yield was 3.8g.

Step 2: Complexation

A 50 mL Schlenk tube flask was charged with7-(4-isopropylphenyl)imidazo[1,2-f]phenanthridine (3.8 g, 11.3 mmol) andtris(acetylacetonate)iridium(III) (1.11 g, 2.26 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees10 (1.2 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=464, 492 nm (CH₂Cl₂ solution at room temperature), CIE=(0.20,0.32).

Example 8 Preparation of es16

Step 1: Ligand synthesis

To a 500 mL round flask was added 7-chloroimidazo[1,2-f]phenanthridine(5.2 g, 20.6 mmol, prepared from the general procedure A),tris(acetylacetonate)iron(III) (0.35 g, 1.0 mmol), 30 mL of NMP and 300mL of dry THF. To this mixture with stirring, 15 mL ofcyclohexylmagnesium chloride solution (2M in ether) was added dropwiseat room temperature. The reaction was completed after the addition. Themixture was quenched by 1N HCl solution. After general work-up andpurification by a silica gel column, yield was 3.4 g.

Step 2: Complexation

A 50 mL Schlenk tube flask was charged with7-cyclohexylimidazo[1,2-f]phenanthridine (3.4 g, 11.2 mmol) andtris(acetylacetonate)iridium(III) (1.1 g, 2.25 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees8 (1.5 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=462, 486 nm (CH₂Cl₂ solution at room temperature), CIE=(0.17,0.27).

Example 9 Preparation of es18

Step 1: Ligand synthesis

To a 500 mL round flask was added 7-chloroimidazo[1,2-f]phenanthridine(5.1 g, 20 mmol, prepared from the general procedure A),2,4,6-triisopropylphenylboronic acid (9.9 g, 40 mmol), Pd₂(dba)₃ (0.92g, 1.0 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos,1.64 g, 4.0 mmol), potassium phosphate tribasic (12.7 g, 60 mmol), and200 mL of toluene. The reaction was heated to reflux and stirred under anitrogen atmosphere for 72 hours. After cooling, the mixture waspurified by a silica gel column. Yield was 2.6 g.

Step 2: Complexation

A 50 mL Schlenk tube flask was charged with7-(2,4,6-triisopropylphenyl)imidazo[1,2-f]phenanthridine (2.6 g, 6.2mmol) and tris(acetylacetonate)iridium(III) (0.61 g, 1.2 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 48 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive es18 (0.3 g). ¹H NMR result confirmed the desired compound. λ_(max)of emission=464, 488 nm (CH₂Cl₂ solution at room temperature),CIE=(0.17, 0.29).

Example 10 Preparation of es20

Step 1

To a 1 L round flask was added 7-methylimidazo[1,2-f]phenanthridine (5.7g, 24.5 mmol, prepared from the general procedure A), and 200 mL of dryDMF. To this mixture with stirring, 100 mL of N-bromosuccinimide DMFsolution (4.6 g, 25.7 mmol) was added dropwise at room temperature inthe dark. The reaction mixture was continued to stir overnight. Then themixture was poured into 1 L of water with stirring. The precipitate wascollected by filtration, and further washed with copious amount ofwater, and last with MeOH (50 mL×2), and then dried. Yield of3-bromo-7-methylimidazo[1,2-f]phenanthridine was 6.5 g.

Step 2

To a 500 mL round flask was added3-bromo-7-methylimidazo[1,2-f]phenanthridine (6.2 g, 20 mmol),2,6-dimethylphenylboronic acid (9.0 g, 60 mmol), Pd₂(dba)₃ (4.58 g, 5.0mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 8.2 g,20 mmol), potassium phosphate tribasic (17.0 g, 80 mmol), and 200 mL oftoluene. The reaction was heated to reflux and stirred under a nitrogenatmosphere for 84 hours. After cooling, the mixture was purified by asilica gel column. Yield was 4.0 g.

Step 3

A 50 mL Schlenk tube flask was charged with3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridine (3.3 g, 10mmol) and tris(acetylacetonate)iridium(III) (0.98 g, 2.0 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 48 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive es20 (0.8 g). ¹H NMR result confirmed the desired compound. λ_(max)of emission=466, 492 nm (CH₂Cl₂ solution at room temperature),CIE=(0.17, 0.30).

Example 11 Preparation of es21

Step 1

To a 1 L round flask was added 6,7-dimethylimidazo[1,2-f]phenanthridine(13.0 g, 52.8 mmol, prepared from the general procedure A), and 400 mLof dry DMF. To this mixture with stirring, 150 mL of N-bromosuccinimideDMF solution (10.3 g, 58 mmol) was added dropwise at room temperature inthe dark. The reaction mixture was continued to stir overnight. Then themixture was poured into 1 L of water with stirring. The precipitate wascollected by filtration, and further washed with copious amount ofwater, and last with MeOH (50 mL×2), and dried. Yield of3-bromo-6,7-dimethylimidazo[1,2-f]phenanthridine was 14.7 g.

Step 2

To a 500 mL round flask was added3-bromo-6,7-dimethylimidazo[1,2-f]phenanthridine (6.5 g, 20 mmol),2,6-dimethylphenylboronic acid (9.0 g, 60 mmol), Pd₂(dba)₃ (4.58 g, 5.0mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 8.2 g,20 mmol), potassium phosphate tribasic (17.0 g, 80 mmol), and 200 mL oftoluene. The reaction was heated to reflux and stirred under a nitrogenatmosphere for 84 hours. After cooling, the mixture was purified by asilica gel column. Yield was 2.6 g.

Step 3

A 50 mL Schlenk tube flask was charged with3-(2,6-dimethylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine (2.6 g,7.4 mmol) and tris(acetylacetonate)iridium(III) (0.73 g, 1.5 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 48 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive es21 (0.35 g). ¹H NMR result confirmed the desired compound.λ_(max) of emission=460, 490 nm (CH₂Cl₂ solution at room temperature),CIE=(0.16, 0.27).

Example 12 Preparation of es26

Step 1

To a 500 mL round flask was added5-bromo-7-tert-butylimidazo[1,2-f]phenanthridine (3.9 g, 11 mmol,prepared from general procedure A), 2,6-dimethylphenylboronic acid (3.5g, 23 mmol), Pd₂(dba)₃ (0.51 g, 0.56 mmol),2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 0.91 g, 2.2mmol), potassium phosphate tribasic (7.2 g, 34 mmol), and 60 mL oftoluene. The reaction was heated to reflux and stirred under a nitrogenatmosphere for 48 hours. After cooling, the mixture was purified by asilica gel column. Yield was 1.2 g.

Step 2

A 50 mL Schlenk tube flask was charged with5-(2,6-dimethylphenyl)-7-tert-butylimidazo[1,2-f]phenanthridine (0.40 g,1.1 mmol) and tris(acetylacetonate)iridium(III) (0.10 g, 0.2 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 24 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive fac-tris iridium(III) (0.01 g). ¹H NMR result confirmed the desiredcompound. λ_(max) of emission=462, 488 nm (CH₂Cl₂ solution at roomtemperature).

Example 13 Preparation of es22

Step 1

To a 500 mL round flask was added3-bromo-6,7-dimethylimidazo[1,2-f]phenanthridine (8.2 g, 25.2 mmol),2,6-dichlorophenylboronic acid (19.2 g, 100.9 mmol). Pd₂(dba)₃ (2.29 g,2.5 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 4.11g, 10.0 mmol), potassium phosphate tribasic (26.7 g, 126 mmol), and 250mL of toluene. The reaction was heated to reflux and stirred under anitrogen atmosphere for 48 hours. After cooling, the mixture waspurified by a silica gel column. Yield of3-(2,6-dichlorophenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine was 2.4g.

Step 2

To a 500 mL round flask was added3-(2,6-dichlorophenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine (2.4 g,6.1 mmol), phenylboronic acid (3.74 g, 30 mmol), Pd₂(dba)₃ (1.1 g, 1.2mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 1.97 g,4.8 mmol), potassium phosphate tribasic (7.64 g, 36 mmol), and 100 mL oftoluene. The reaction was heated to reflux and stirred under a nitrogenatmosphere for 12 hours. After cooling, the mixture was purified by asilica gel column. Yield of3-(2,6-diphenylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine was 0.9g.

Step 3

A 25 mL Schlenk tube flask was charged with3-(2,6-diphenylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine (0.095g, 0.2 mmol) and tris(acetylacetonate)iridium(III) (0.025 g, 0.05 mmol).The reaction mixture was stirred under a nitrogen atmosphere and heatedin a sand bath at 240° C. for 24 hours. After cooling, the solidifiedmixture was dissolved in CH₂Cl₂ and further purified by a silica gelcolumn to give es22 (0.01 g). ¹H NMR result confirmed the desiredcompound. A, of emission=468, 496 nm (CH₂Cl₂ solution at roomtemperature), CIE=(0.19, 0.35).

Example 14 Preparation of es25

A 50 mL Schlenk tube flask was charged with7-n-dodecylimidazo[1,2-f]phenanthridine (3.66 g, 9.34 mmol prepared viageneral procedure A) and tris(acetylacetonate)iridium(III) (0.92 g, 1.87mmol). The reaction mixture was stirred under a nitrogen atmosphere andheated in a sand bath at 240° C. for 48 hours. After cooling, thesolidified mixture was dissolved in CH₂Cl₂ and further purified by asilica gel column to give es25 (1.5 g). ¹H NMR result confirmed thedesired compound.

Example 15 Preparation of es9

Step 1: Synthesis of 2-(1,3,2-dioxaborinan-2-yl)benzonitrile

49.0 g (334 mmol) 2-cyanobenzeneboronic acid and 25.9 g (340 mmol)1,3-propanediol were dissolved in 1 L CH₂Cl₂ with stirring in a 2 Lround bottom flask for 20 h. The solution was then poured over a filterwith suction to remove gummy solids. The filtrate was then dried withanhydrous MgSO₄ to remove residual water, filtered and evaporated ofsolvent to give light-colored oil. The oil was then dissolved in CH₂Cl₂and purified on a silica gel plug using CH₂C₂ as eluent. The productfractions were evaporated down to give the product as clear oil (35.7 g,57.2% yield).

Step 2: Synthesis of 2-(tert-butyl)-6-aminophenanthridine

35.7 g (190 mmol) 2-(1,3,2-dioxaborinan-2-yl)benzonitrile, 31.9 g (158mmol) 2-bromo-4-(tertbutyl)aniline, 3.6 g (3.16 mmol)tetrakis(triphenylphosphine) palladium(0) and 59.0 g (427 mmol) K₂CO₃were heated to reflux in a 2 L flask containing 400 ml toluene and 300mL ethanol. The reaction mixture was heated for 19 hours under constantN₂ purge. HPLC of the reaction mixture indicated consumption of thestarting aniline. The mixture was cooled and then filtered to remove thebase. The base was washed with EtOAc to remove trace organic. Thecombined filtrate was evaporated down to give impure oil. The oil waspurified on a column of silica using 95/5/.05 CH₂Cl₂/MeOH/NH₄OH aseluent to obtain separation. The product fractions were evaporated ofsolvent and the resultant residue recrystallized from CH₂Cl₂/hexanes toyield 14.0 g of the target compound as white solids (35.5% yield,confirmed by GC-MS).

Step 3: Synthesis of es9 ligand

13.0 g (52 mmol) 2-(tert-butyl)-6-aminophenanthridine, 12.3 g (78 mmol,50% v/v in H₂O) chloroacetaldehyde, and 8.74 g (104 mmol) sodiumbicarbonate were added to a 500 mL flask and refluxed in 200 mL2-propanol for 35 hours under N₂ atmosphere. Upon completion, themixture was cooled whereupon TLC and HPLC indicated complete consumptionof the starting phenanthridine. The mixture was taken up in ethylacetate and filtered to remove base. The filtrate was then evaporated toyield light amber oil. The oil was purified on a column of silica using95/5/.05 CH₂Cl₂/MeOH/NH₄OH as eluent. Alternatively, the ligand could bepurified using automated chromatography with an Al₂O₃ column and agradient of 2% EtOAc/hexanes—20% EtOAc/hexanes as eluent. The productfractions from these purifications were evaporated of solvent andrecrystallized from methylene chloride/hexanes to yield a total of 10.8g es9 ligand as a white solid (76.1% yield, NMR confirmed).

Step 4

10.6 g (38.7 mmol) es9 ligand and 4.76 g (9.7 mmol) Ir(acac)₃ were addedto a 50 mL Schlenk tube equipped with a stirbar, 20 drops of tridecanewere added, the tube was sealed with a septa and vacuum degassedthoroughly with N₂. The tube was submersed in a sand bath and heated at245° C. for 72 hours under N₂ atmosphere. The cooled mixture was thentaken up in CH₂Cl₂ with sonication to dissolve the impurities. Themixture was filtered in vacuo and the solids rinsed with CH₂Cl₂ andhexanes to give dark yellow solids in the amount of 8.5 g. The solidswere then dissolved in 1 L boiling chlorobenzene and poured over acelite mat (hot) to remove impurities. The resultant filtrate wasevaporated to 500 mL allowing the dopant to recrystallize as brightyellow solids (6.5 g, 66.4% yield, NMR confirmed, 99.3% HPLC assay). Asa further method of purification, 3.5 g of the dopant was sublimed in athree zone sublimator at 370° C. and 1.0×10⁻⁵ Torr vacuum to give 400 mges9 as a bright yellow solid (100% HPLC assay).

Example 16 Preparation of es8

Step 1: Synthesis of 2-(n-hexyl)-6-aminophenanthridine

13.1 g (69.8 mmol) 2-(1,3,2-dioxaborinan-2-yl)benzonitrile, 16.3 g (63.4mmol) 2-bromo-4-hexylaniline, 1.62 g (1.40 mmol)tetrakis(triphenylphosphine) palladium(0), and 23.6 g (171 mmol)potassium carbonate where refluxed in 250 ml toluene and 100 ml EtOHunder N₂ atmosphere for 20 hours. HPLC and TLC revealed almost completeconsumption of the aniline. The reaction mixture was cooled and passedthrough a filter. The solids were washed with ethyl acetate to removeorganics from the collected base. The filtrate was then evaporated downand dried on silica. The sample was purified using silica gelchromatography with 100% ethyl acetate as the eluent. The productfractions were then evaporated down to a minimal amount and hexanesadded to crystallize the product as off white solids (7.05 g, 39.8%yield, GC-MS confirmed).

Step 2: Synthesis of es8 ligand

7.02 g (25.2 mmol) 2-(n-hexyl)-6-aminophenanthridine, 2.99 g (37.8 mmol,50% v/v in H₂O) chloroacetaldehyde, and 4.24 g (50.4 mmol) sodiumbicarbonate were added to a 500 mL flask and refluxed in 150 mL2-propanol for 20 hours under N₂ atmosphere. Upon completion, themixture was cooled whereupon TLC and HPLC indicated complete consumptionof the starting phenanthridine. The mixture was taken up in EtOAc andfiltered to remove base. The filtrate was then evaporated to yield lightamber oil. The oil was then dried on silica and purified on a column ofsilica using 70% ethyl acetate/hexanes→100% ethyl acetate as eluent. Theproduct fractions from this purification were evaporated of solvent andrecrystallized from ethyl acetate/hexanes to yield a total of 4.9 g es8ligand as a white solid (55.1% yield, GC-MS confirmed).

Step 3

A 50 ml schlenk tube was charged with 2.9 grams (9.6 mmol) of es8ligand, 0.94 g (1.9 mmol) iridium acetylacetonate, and 20 drops oftridecane. The reactor was evacuated and backfilled three times withnitrogen gas. The reaction was heated to 240° C. for 70 hours. Thereaction was cooled and dichloromethane was added. The product waspurified by column chromatography with dichloromethane as the eluent.The fractions containing the desired product were combined and thesolvent was removed by rotary evaporation. The product was crystallizedfrom toluene to yielded 300 mg es8, which was further purified bysublimation.

Example 17 Preparation of es13

Step 1: Synthesis of 2-Bromophenanthridinone

99.8 g (511 mmol) phenanthridinone was added to a 3 L multi-neck flaskequipped with a stir arm and condenser. 1.2 L glacial acetic acid wasadded and the mixture was allowed to stir at 150 rpm and heated toreflux. 90 g (562 mmol) Br₂ suspended in 100 ml acetic acid was added tothe refluxing solution dropwise over a period of 3 hours. Afteraddition, the mixture was assayed and revealed to be ˜80% complete.Based on this assay, an additional 20 g of Br₂ (in 30 mL acetic acid)was added dropwise to the mixture at reflux. After this addition, theassay was >90% complete. A final 20 g Br₂ (in 30 mL acetic acid) wasadded dropwise and the mixture allowed to stir for 1 hour afteraddition. The final assay was >97%. The mixture was cooled and 1 L ofwater was added and the mixture filtered. The wet solids were thenstirred in aqueous sodium thiosulfate to destroy residual bromine andrefiltered. These solids were rinsed with H₂O and allowed to dry invacuo to remove residual water. The solids were then recrystallized fromnitrobenzene (>2 liters) and collected on a funnel to give 128 g2-bromophenanthridinone (90.8% yield).

Step 2: Synthesis of 2-Bromo-6-chlorophenanthridine

36.7 g (139 mmol) 2-bromophenanthridinone and 30.7 g (147 mmol) PCl₅were added to a 1 L multi-neck flask (equipped with stir arm, condenser,and base trap) along with 350 mL POCl₃ and heated at 93° C. for 16 hours(note: evolution of HCl gas was predominant-destroyed by base trap).Afterwards, the mixture was assayed to determine complete consumption of2-bromophenanthridinone. A dean stark trap was connected to the flask toremove the solvent by ½ volume. Subsequently, equal volumes of toluenewere added and distilled off to remove majority of POCl₃. After thethird addition of toluene, the volume was reduced to 300 mL's and theremainder of the solvent removed via rotary evaporation. The solids werethen recrystallized from toluene and dried to give 30.8 g (78.6% yield,98% assay) 2-bromo-6-chlorophenanthridine as off white solids (GC-MSconfirmed).

Step 3: Synthesis of es13-i1

20 g 4 A dried molecular sieves were added to a 2 L multi-neck flaskequipped with a stir arm and condenser. 73.8 g (252 mmol)2-bromo-6-chlorophenanthridine and 79.4 g (756 mmol) aminoacetaldehydedimethylacetal were added to the flask along with 750 mL anhydrousdiglyme. The mixture was heated at 135° C. using mechanical stirring for18 hours under N₂ atmosphere. HPLC of the mixture revealed completeconsumption of the starting material. The reaction was then cooled andenriched with ethyl acetate. The caked solids were removed from theflask side walls with scrapping. The mixture was then filtered in vacuoand the filtrate set aside. The solids from the funnel were then crushed(when dried) using a mortar and pestle and added to a 1 L flask andrefluxed in 600 mL chlorobenzene. The chlorobenzene mixture was filteredand the filtrates combined. Solvent was then removed via rotaryevaporation to give dark solids. The solids were then purified on alarge column of silica using CH₂Cl₂ and CH₂Cl₂/MeOH as eluent (Note:when the CH₂Cl₂ solution of the product was put on top of the column,not all of the solids were solubilized. Through addition of extraeluent, the solids did eventually dissolve). After the lengthychromatography, the product fractions were evaporated of solvent and thesolids cleaned with CH₂Cl₂/hexanes. Filtration of the solids gave 62.0grams of the title compound when dried (83.1% yield, NMR confirmed).

Step 4: Synthesis of es13 ligand

3.12 g (10.5 mmol) 7[bromo]-imidazo[1,2-f]phenanthridine, 3.93 g (26.2mmol) 2,6-dimethylphenylboronic acid, 0.18 g (0.53 mmol)2-(dicyclohexylphosphino)biphenyl, 0.13 g (0.14 mmol) Pd₂(dba)₃ and 6.68g (31.5 mmol) potassium phosphate were added to a 50 mL air free flaskequipped with a stir bar and vacuum degassed with N₂. 20 mL anhydrousm-xylene was added and the mixture set to 130° C. under N₂ atmosphere.HPLC of the mixture after 16 hours revealed complete consumption of thestarting phenanthridine. The mixture was enriched with ethyl acetate andmethylene chloride and filtered to remove the base. The filtrate wasthen pooled with 854-8741-076 (1 g scale rxn) and evaporated down togive a dark oil. The oil was dried on silica (using methylene chloride)and the product chromatographed using automated chromatography with agradient of 5% EtOAc/hexanes→50% EtOAc/hexanes over a period of 1 hour.The pure fractions were evaporated down to give 3.40 g of a khakicolored solid (76.2% yield, 98% HPLC assay, NMR confirmed).

Step 5

3.40 g (10.6 mmol) 7-(2,6-dimethylphenyl)-imidazo[1,2-f]phenanthridineand 1.30 g (2.6 mmol) iridium(III) acetylacetonate were added to a 25 mLSchlenk tube equipped with a stir bar along with 12 drops of tridecane.The flask was sealed and vacuum degassed with N₂. The mixture was thensubmerged in a sand bath and heated at 250° C. under N₂ atmosphere for96 hours. The mixture was then taken up in methylene chloride andpurified on a column of silica using methylene chloride as the eluent.The product fractions were evaporated of solvent to give crude dopant.The solids were then recrystallized from methylene chloride/methanol togive 2.1 g of es13 as a yellow solid (68.9% yield, HPLC assay 99.5%, NMRconfirmed).

Example 18 Preparation of es15

Step 1: Preparation of 2-(n-butyl)-6-aminophenanthridine

20.0 g (87.7 mmol) 2-(1,3,2-dioxaborinan-2-yl)benzonitrile, 13.7 g (73.1mmol) 2-bromo-4-butylaniline, 1.70 g (1.46 mmol)tetrakis(triphenylphosphine)palladium(0), and 27.2 g (198 mmol)potassium carbonate where refluxed in 400 mL toluene and 200 mL ethanolunder N₂ atmosphere for 20 h. HPLC and TLC revealed almost completeconsumption of the aniline. An additional 1.8 g2-(1,3,2-dioxaborinan-2-yl)benzonitrile was added and refluxed continuedfor an additional 18 h. The reaction mixture was cooled and passedthrough a filter. The solids were washed with ethyl acetate to removeorganics from the collected base. The filtrate was then evaporated downand dried on silica. The sample was purified using silica gelchromatography with 100% ethyl acetate as the eluent. The productfractions were then evaporated down to a minimal amount and the productrecrystallized from EtOAc/hexanes to give 12.0 g of the title compoundas light yellow solids (65.9% yield, GC-MS confirmed).

Step 2: Synthesis of es15 ligand

12.0 g (48.0 mmol) 2-(n-butyl)-6-aminophenanthridine, 11.4 g (72.0 mmol,50% v/v in H₂O) chloroacetaldehyde, and 8.06 g (96.0 mmol) sodiumbicarbonate were added to a 500 mL flask and refluxed in 200 mL2-propanol for 20 hours under N₂ atmosphere. Upon completion, themixture was cooled whereupon TLC and HPLC indicated complete consumptionof the starting phenanthridine. The mixture was taken up in EtOAc andfiltered to remove base. The filtrate was then evaporated to yield brownoil. The oil was then dried on silica and purified on a column of silicausing 70% ethyl acetate/hexanes→100% ethyl acetate as eluent. Theproduct fractions from this purification were evaporated of solvent andrecrystallized from ethyl acetate/hexanes to yield a total of 5.22 ges15 ligand as an off-white solid (40.5% yield, NMR confirmed).

Step 3

5.2 g (21.0 mmol) es15 ligand and 2.58 g (5.25 mmol) iridium(III)acetylacetonate were added to a 25 mL Schlenk tube equipped with astirbar. 10 drops of tridecane were added, the tube was sealed with asepta and vacuum degassed thoroughly with N₂. The tube was submersed ina sand bath and heated at 250° C. for 72 h under a N₂ atmosphere. Thecooled mixture was then taken up in CH₂Cl₂ with sonication to dissolvethe impurities. The mixture was filtered in vacuo and the solids rinsedwith CH₂Cl₂ and hexanes to give yellow solids in the amount of 2.74 g.The solids were then dissolved in 130 mL boiling chlorobenzene andpoured over a celite mat (hot) to remove impurities. The resultantfiltrate was evaporated to dryness. The residue was taken up inmethylene chloride and the contents purified on a silica gel columnusing methylene chloride and flash. The product fractions wereevaporated of solvent and the solids recrystallized from chlorobenzeneto yield 1.52 g of es15 as a yellow solid (29.6% yield, NMR confirmed,96.3% HPLC assay), 1.5 g of which was further purified by sublimation ina three zone sublimator at 360° C. and 1.0×10⁻⁵ Torr vacuum to give 160mg of es15 as a bright yellow solid.

Example 19 Preparation of es6

Step 1: Synthesis of 2-isopropyl-phenanthridin-6-ylamine

A 500 ml round bottom flask was charged with 12.2 grams (65.4 mmol) of2-cyanophenylboronic acid propanediol ester, 14.0 g (65.4 mmol) of2-bromo-4-isopropylaniline, 2.27 (2 mmol)tetrakis(triphenylphosphine)palladium, 18.0 g (131 mmol) of potassiumcarbonate, 150 ml toluene, and 50 ml ethanol. The reaction was heated toreflux under N₂ for 18 hours. After cooling to room temperature thereaction was extracted with ethyl acetate and water. The organic waswashed with brine and then dried with magnesium sulfate. The solids werecollected by filtration and the solvent removed from filtrate. Theproduct was purified by silica gel chromatography using 94.5%dichloromethane, 5% methanol, 0.5% ammonium hydroxide as the eluent. Thefractions containing the desired product were combined and the solventremoved. The product was confirmed by NMR and mass spectroscopy.

Step 2: Synthesis of es6 ligand

A 250 ml round bottom flask was charged with 5 grams (21.2 mmol)2-Isopropyl-phenanthridin-6-ylamine, 5 grams (31.8 mmol, 50% solution inwater) chloroacetaldehyde, 3.56 grams (42.4 mmol) sodium bicarbonate,and 150 ml isopropanol. The mixture was heated to reflux for 18 hoursand then cooled to room temperature. Dichloromethane was added and thesolids filtered. The solvent was removed by rotary evaporation and theproduct purified by column chromatography with 40% hexane/ethyl acetateas the eluent. The fractions containing the desired product werecombined and the solvent removed. The product was further purified byKugelrohr distillation. Collected 5.8 grams of es6 ligand.

Step 3

A 50 ml schlenk tube was charged with 2.8 grams (10.8 mmol) of7-Isopropyl-imidazo[1,2-f]phenanthridine and 1.05 g (2.2 mmol) iridiumacetylacetonate. The reactor was evacuated and backfilled three timeswith nitrogen gas. The reaction was heated to 250° C. for 24 hours. Thereaction was cooled and dichloromethane was added and then the solidswere filtered to yield 1.5 grams of a yellow solid. The solids weredissolved in hot 1,2-dichlorobenzene. The mixture was cooled and thesolids filtered to yield 0.4 grams of es6 as a yellow solid. Thematerial was further purified by sublimation.

Example 20 Preparation of es8

A 50 ml schlenk tube was charged with 2.9 grams (9.6 mmol) of es8ligand, 0.94 g (1.9 mmol) iridium acetylacetonate, and 20 drops oftridecane. The reactor was evacuated and backfilled three times withnitrogen gas. The reaction was heated to 240° C. for 70 hours. Thereaction was cooled and dichloromethane was added. The product waspurified by column chromatography with dichloromethane as the eluent.The fractions containing the desired product were combined and thesolvent was removed by rotary evaporation. The product was crystallizedfrom toluene to yielded 300 mg of es8, which was further purified bysublimation.

Example 21 Preparation of es5

Step 1: Synthesis of 9-fluoro-6-phenanthridinamine

To a solution of 2-chloro-4-fluorobenzonitrile (1.0 g, 6.42 mmol),2-aminophenylboronic acid pinacol ester (1.6 g, 7.1 mmol), palladium(II)acetate (0.07 g, 0.32 mmol), amantadine hydrochloride (0.24 g, 1.3 mmol)and cesium carbonate (4.6 g, 14.1 mmol) were added to dioxane previouslydeaerated with nitrogen and heated to reflux for 17 hours. Aftercooling, both distilled water and methylene chloride (50 mL) were addedto the reaction mixture. The solvent layer was separated andconcentrated to give a crude oil that was purified by columnchromatography by first using 1:1 ethyl acetate and hexanes ratiofollowed by 4:1 ethyl acetate/hexanes as the eluants. The pure productwas collected to give 9-fluoro-6-phenanthridinamine (42 g, 32% Yield)whose NMR spectrum is consistent with the proposed structure.

Step 2: Synthesis of 10-fluoro-imidazo[1,2-f]phenanthridine)

9-Fluoro-6-Phenanthridinamine (0.8 g, 3.7 mmol), and a 50% solution ofacetyl chloride (0.4 g, 5.66 mmol) in water containing sodiumbicarbonate (0.6 g, 7.54 mmol) was dissolved in isopropyl alcohol (25mL). The reaction mixture was refluxed for 17 hours under a nitrogenpad. The reaction mixture was cooled to room temperature and theprecipitate vacuum filtered and washed with methylene chloride. Thecrude product was purified by column chromatography using a 1:1 ratio ofethyl acetate and hexanes as the eluants followed by distillation togive 10-fluoro-imidazo[1,2-f]phenanthridine) (0.46 g, 52% yield).

Step 3

A 50 ml schlenk tube was charged with 2.1 grams (9.6 mmol) of10-fluoro-imidazo[1,2-f]phenanthridine, 0.87 g (1.9 mmol) iridiumacetylacetonate, and 15 drops of tridecane. The reactor was evacuatedand backfilled three times with nitrogen gas. The reaction was heated to230° C. for 40 hours. The reaction was cooled and dichloromethane wasadded. The product was purified by column chromatography withdichloromethane as the eluent. The fractions containing the desiredproduct were combined and the solvent was removed by rotary evaporation.The product was crystallized from a dichloromethane/hexane mixture toyield 500 mg of es5, which was further purified by sublimation.

Example 22 Preparation of es19

Step 1: Synthesis of 3-tert-butylphenylboronic acid

To a solution of dry THF (10 mL) was added magnesium (1.25 g, 52 mmol),3-t-butyl bromobenzene (2.0 g, 9.4 mmol) and a crystal of iodine. Thereaction was first heated slightly until the reaction started and thenremoved. The remaining 3-t-butyl bromobenzene (8.0 g, 37.7 mmol) wasadded via an addition funnel until the spontaneous refluxing stopped.The reaction mixture was heated to reflux for 2 hours. The Grignard wastransferred via a syringe into a cooled solution (−40° C.) of trimethylborate dissolved in THF and added over a 10 minute period. The reactionmixture was warmed to room temperature overnight. Ethyl acetate anddistilled water were added to the reaction mixture and the layersseparated. The organics were washed with brine and dried over magnesiumsulfate. The solvent was concentrated and the product purified by asilica gel column using 10% ethyl acetate and hexanes as the eluants togive 3-t-butylphenyl boronic acid (4.0 g, 46% yield) as a white solid.The product was confirmed by GCMS and was used directly in the nextstep.

Step 2: Synthesis of 2-amino-3′,5-di-tert-butyl biphenyl

Added together were 3-t-butylphenylboronic acid (4.0 g, 22.4 mmol),2-bromo-4-t-butyl aniline (4.3 g, 18.7 mmol), palladium(II)acetate (0.11g, 0.468 mmol), triphenyl phosphine (0.5 g, 1.8 mmol), and 25 mL of a 2M solution of potassium carbonate in 36 mL of ethylene glycol dimethylether. The reaction mixture was heated at reflux for 18 hours. Thereaction was cooled to room temperature and the aqueous phase wasseparated from the organic phase. The aqueous phase was extracted withethyl acetate. The organic extractions were combined, dried overmagnesium sulfate filtered and concentrated. The crude product waspurified by column chromatography using 20% ethyl acetate and hexanes asthe eluants. The pure product 2-amino-3′,5-di-tert-butyl biphenyl (3.0g, 57% yield) was collected as a white solid whose NMR was consistentwith the proposed structure.

Step 3: Synthesis of N-formyl-2-amino-3′,5-di-tert-butyl biphenyl

Added 2-amino-3′,5-di-t-butyl biphenyl (2.0 g, 7.11 mmol) to a solutionof formic acid and heated to reflux for 16 hours. After cooling, water(25 mL) was added the product and the precipitate collected by vacuumfiltration. The crude product was dissolved into ethyl acetate, washedwith water. The organics were dried over magnesium sulfate andconcentrated and purified by column chromatography using 10% ethylacetate and hexanes as the eluants to give the pureN-formyl-2-amino-3′,5-di-t-butyl biphenyl (1.8 g, 82% yield) asdetermined by GCMS.

Step 4: Synthesis of 2,9-di-tert-butylphenanthridinone

The above compound, N-formyl-2-amino-3′,5-di-t-butyl biphenyl (6.5 g, 21mmol) was dissolved into 50 mL of chlorobenzene to which 5 equivalentsof di-t-butyl peroxide was added. The reaction mixture was heated to110° C. for 72 hours. The reaction mixture was concentrated in half andcooled to 0° C. The precipitate that formed was collected by vacuumfiltration. The off-white solid was washed with hexanes to give2,9-di-tert-butylphenanthridinone as determined by GCMS and not purifiedany further.

Step 5: Synthesis of 2,9-di-tert-butyl-6-chlorophenanthridine

The above 2,9-di-t-butylphenanthridinone (3.0 g, 9.7 mmole) was added toa reaction flask containing phosphorus pentachloride (3.0 g, 14.6 mmole)and 50 mL of phosphoryl chloride. The reaction mixture was refluxedovernight, cooled to room temperature and diluted with toluene. Theexcess phosphoryl chloride and toluene were removed by a rotaryevaporator. The residue was dissolved into ethyl acetate and washed withdistilled water followed by brine. The solvent layer was dried overmagnesium sulfate, filtered and concentrated to give the desired2,9-di-tert-butyl-6-chlorophenanthridine (3.0 grams, 98%) as an offwhite solid. The product was confirmed by GC Mass Spec and not purifiedfurther but used directly in the next step.

Step 5: Synthesis of 7,10-di-tert-butyl-imidazo[1,2-f]phenanthridine

2,9-Di-t-butyl-6-chlorophenanthridine (3.7 grams, 11.0 mmole) was addedto a reaction flask containing aminoacetaldehyde dimethylacetal (2.4grams, 23 mmole) dissolved into 200 mL of diglyme, heated to reflux andstirred under a nitrogen atmosphere. After 96 hours the reaction wascomplete as determined by TLC. The reaction mixture was cooled to roomtemperature and the excess solvent removed by distillation. The residuewas taken up into methylene chloride. The solvent was dried overmagnesium sulfate filtered and concentrated. The crude product waspurified by silica gel chromatography using 10% ethyl acetate and 90%methylene chloride as the eluents. The purified product was collected,washed with hexanes, and dried to give7,10-di-tert-butyl-imidazo[1,2-f]phenanthridine (2.0 grams, 56% yield)as a white solid.

Step 6

A 50 ml schlenk tube was charged with 2.0 grams (6.1 mmol) of10-fluoro-imidazo[1,2-]phenanthridine, 0.84 g (1.7 mmol) iridiumacetylacetonate, and 10 drops of tridecane. The reactor was evacuatedand backfilled three times with nitrogen gas. The reaction was heated to240° C. for 18 hours. The reaction was cooled and dichloromethane wasadded. The product was purified by column chromatography withdichloromethane as the eluent. The fractions containing the desiredproduct were combined and the solvent was removed by rotary evaporation.The product was crystallized from a dichloromethane/hexane mixture toyield 0.6 g of es19, which was further purified by sublimation.

Example 23 Preparation of es14

Step 1: Synthesis of 3,5-dimethyl-6-phenanthridinamine

Added together 2-cyanophenylboronic acid pinacol ester (13.7 g, 60mmol), 2-bromo-4,6-dimethylaniline (10.0 g, 50 mmol),tetrakis(triphenylphosphine)palladium(0) (2.3 g, 2.0 mmol) and potassiumcarbonate (18.6 g, 138.21 mol) to a 125 mL of a 95/5 mixture oftoluene/methanol. The solvents were degassed and the reaction mixtureheated to reflux for 48 hours. After cooling, the reaction mixture wasvacuum filtered and the organics evaporated and crude product waspurified using silica gel column chromatography treated withtriethylamine and 1:9 ethyl acetate and methylene chloride mixture asthe eluants. The pure product was collected and concentrated to give3,5-dimethyl-6-phenanthridinamine (9.1 g, 82% Yield).

Step 2: Synthesis of 5,7-dimethyl-imidazo[1,2-f]phenanthridine)

3,5-Dimethyl-6-phenanthridinamine (8.6 g, 39 mmol), a 50% solution ofacetyl chloride (4.6 g, 58 mmol) in water, sodium bicarbonate (6.5 g,77.4 mmol) in 258 mL of isopropyl alcohol were heated to reflux for 40hours. After cooling the crude product was dissolve into methylenechloride and vacuum filtered. The filtrate was concentrated and thecrude product was crystallized in methylene chloride and ethyl acetatemixture. The pure product was collected by vacuum filtration to give5,7-dimethyl-imidazo[1,2-f]phenanthridine) (3.8 g, 40% yield) asdetermined by NMR.

Step 3

3.7 g (15.0 mmol) 5,7-dimethyl(imidazo[1,2-f]phenanthridine) and 1.85 g(3.76 mmol) Ir(acac)₃ were added to a 50 mL Schlenk tube equipped with astirbar. 12 drops tridecane was added and the tube sealed and vacuumdegassed with N₂. The tube was then immersed in a sand bath and heatedto 250° C. for 72 hours. The reaction mixture was cooled and thecontents sonicated with CH₂Cl₂ to dissolve. The yellow solids werefiltered and heated in chlorobenzene. The solution was filtered throughCelite and concentrated to induce crystallization. The solids werefiltered to yield 600 mg es14 as a yellow solid that was furtherpurified by sublimation.

Example 24 Preparation of es27

Step 1: Synthesis of 2-amino-2′-methyl-biphenyl

Added together 2-methylphenyl boronic acid (24.7 g, 181 mmol), 2-bromoaniline (25.7 g, 151 mmol), palladium(II)acetate (0.85 g, 3.78 mmol),triphenylphosphine (4.0 g, 15.1 mmol), a 2 M solution of potassiumcarbonate (204 mL) and ethylene glycol dimethyl ether (223 mL) andheated the reaction mixture at reflux for 18 hours. After the reactionwas cooled to room temperature, the aqueous phase was separated from theorganic phase. The aqueous phase was extracted with ethyl acetate andthe organic extractions were combined, dried over magnesium sulfate andfiltered. The crude product was purified by silica gel columnchromatography using 10% ethyl acetate in hexanes as the eluants. Thepure fractions were collected, combined and concentrated to give2-amino-2′-methyl-biphenyl (23.5 g, 84.8% yield) whose structure wasconfirmed by GCMS and NMR.

Step 2: Synthesis of N-ethoxycarbonyl-2-amino-2′methyl biphenyl

The above compound, 2-amino-2′-methyl-biphenyl (11.0 g, 60 mmol) wasadded to dry toluene (250 mL) containing triethyl amine (24 g, 24 mmol)and stirred under a nitrogen pad. Ethyl chlorofomate (26 g, 240 mmol)was slowly added to the stirred solution via a syringe. The reactionmixture was washed with brine and the organics separated, dried overmagnesium sulfate and concentrated to giveN-ethoxycarbonyl-2-amino-2′methyl biphenyl as a colorless oil (7.0 g,46% yield) whose structure was confirmed by GCMS and NMR.

Step 3: Synthesis of 10-methyl-phenanthridinone

The above compound, N-ethoxycarbonyl-2-amino-2′methyl biphenyl (6.7 g,26 mmol) was added to polyphosphoric acid (15 g) and heated to 170° C.overnight. After cooling, water was added and the white precipitatecollected by vacuum filtration to give the 10-methyl-phenanthridinone(3.5 g, 65% yield) whose structure was consistent with CGMS and NMR.

Step 4: Synthesis of 6-chloro-10-methylphenanthridine

The above compound, 10-methyl-phenanthridinone (4.0 grams, 19 mmole) wasadded to a reaction flask containing phosphorus pentachloride (6.0grams, 0.29 mole) and phosphoryl chloride (50 mL). The reaction mixturewas refluxed for 4 hours, cooled to room temperature and diluted withtoluene. The excess phosphoryl chloride and toluene were removed by arotary evaporator. The residue was dissolved into ethyl acetate andwashed with distilled water followed by brine. The solvent layer wasdried over magnesium sulfate, filtered and concentrated to give6-chloro-10-methylphenanthridine (4.1 grams, 95%) as an off-white solid.The product was confirmed by Mass Spec and NMR and not purified furtherbut used directly in the next step.

Step 5: Synthesis of es27i-1

To a solution of diglyme (100 mL) was added the above6-chloro-10-methylphenanthridine (1.8 g, 7.9 mmol) and2-bromo-4-isopropylanaline (3.4 g, 15.8 mmol). The reaction mixture wasstirred under a nitrogen pad for 3 hours at 160° C. After cooling, theprecipitate was vacuum filtered, washed with ethyl acetate followed byhexanes to give es27i-1 (2.5 g, 78% yield) as a beige solid.

Step 6: Synthesis of10-isopropyl-3-methyl-8b,13-diaza-indeno[1,2-f]phenanthrene

The above compound, (3.5 g, 8.7 mmol) was dissolved into toluenecontaining triphenylphosphine (0.45 g, 1.7 mmol), palladium acetate(0.12 g, 0.5 mmol), potassium carbonate (3.6 g, 26 mmol). The reactionmixture was refluxed overnight under a nitrogen pad. The reactionmixture was cooled to room temperature and washed with distilled waterfollowed by brine. After separating the organic layers, the es27 ligandproduct was purified on a silica gel column.

Step 7

A 50 ml round bottom flask was charged with 1.8 g (5.5 mmol) of10-isopropyl-3-methyl-8b,13-diaza-indeno[1,2-f]phenanthrene, 0.67 g (1.4mmol) iridium acetylacetonate and 20 ml ethylene glycol. The reactionwas heated to reflux under nitrogen for 24 hours. The reaction wascooled and methanol was added followed by filtration of the yellowsolids. The solids were dissolved in dichloromethane and purified bycolumn chromatography with dichloromethane as the eluent. The fractionscontaining the desired product were combined and the solvent was removedby rotary evaporation. The product was crystallized from chlorobenzeneto yield 0.3 g of es27.

Example 25 Preparation of es17

Step 1: Synthesis of es17i-1

A three neck 1 L round bottom flask was charged with2,6-dibromo-4-tert-butyl aniline (38 g, 0.124 mole), 2-cyanophenylbornicacid pinacol ester (10 g, 0.044 mole), K₃PO₄. H₂O (35.4 g, 0.154 mole),PdCl₂(PPh₃)₂ (1.8 g, 2.6 mmole) and anhydrous toluene (500 ml). Thereaction mixture was heated to 100° C. under nitrogen for 6 hrs. Thereaction mixture was then concentrated to dryness and subjected tocolumn chromagraphy to get es17i-1 (5.65 g, 39%).

Step 2: Synthesis of es17i-2

To a mixture of es17i-1 (2.75 g, 8.4 mmole), sodium bicarbonate (1.4 g,16.7 mmole) in 2-propanol (75 ml) was added chloroacetaldehyde (50%aqueous soln. 1.96 g). After the reaction mixture was heated at 75° C.for 5 hrs., the solvent was removed. The residue was redissolved inmethylene chloride and washed with water. The organic fractions werecombined, dried over sodium sulfate, filtered, and concentrated invacuo. The crude mixture was purified by chromatography on silica gelusing hexane/ethyl acetate (80/20) to give pure es17i-2 (2.52 g, 85%)

Step 3: Synthesis of es17i-3

A three neck 1 L round bottom flask was charged with es17i-2 (4.5 g,12.7 mmol), 4-tert-butylphenylbornic acid(5.09 g, 29 mmol), sodiumcarbonate (9.22 g, 87 mmol), Pd(PPh)₄ (0.99 g, 0.86 mmol), 50 ml ofwater and 400 ml of toluene. The reaction mixture was heated to 100° C.under nitrogen for 17 hrs. The reaction mixture was diluted withmethylene chloride and washed by brine. The organic fractions werecombined, dried over sodium sulfate, filtered, and concentrated invacuo. The crude mixture was purified by chromagraphy on silica gelusing hexane/ethyl acetate (80/20) to give pure es17i-3 (5.05 g, 97%).

Step 4

A 25 ml 2 neck flask was charged with es17i-3 (3.41 g, 8.38 mmol),Ir(acac)₃ (821.24 mg, 1.67 mmol) and 30 drops of tridecane. The flaskwas vacuum and back refilled with nitrogen for three times and then heatto 220° C. for 65 hrs. The reaction mixture was dissolved in methylenechloride and subjected to column chromatography to obtain es17 (1 g, 42%yield).

Example 26 Preparation of es23

Step 1: Synthesis of 3-(tributyltin)-imidazo[1,2-f]phenanthridine

A three neck round bottom flask was charged withimidazo[1,2-f]phenanthridine (11.6 g, 53.21 mmol) and 600 mL ofanhydrous THF. A solution of n-butyl lithium (2 M solution incyclohexane, 39.9 mL, 79.8 mmol) was added to the reaction mixture at−78° C. After stirring at −78° C. for 2 hrs; tributyltin chloride (25.97g, 79.8 mmol) was added at −78° C. The reaction mixture was stirred at−78° C. for two hours. The reaction mixture was concentrated undervacuum to dryness and subjected to column chromatography (Silica gelpretreated with triethylamine, 50% EtOAC in hexanes) to obtain the titlecompound (24.61 g, 91% yield).

Step 2: Synthesis of 3-(2,6-dichlorophenyl)-imidazo[1,2-f]phenanthridine

A 250 ml round bottom flask was charged with3-(tributyltin)-imidazo[1,2-f]phenanthridine (23.87 g, 47 mmol),2,6-dichloroiodobenzene (12.84 g, 47.08 mmol), PdCl₂(PPh₃)₂ (1.97 g,2.82 mmol) and 170 ml of anhydrous para-xylene. The reaction mixture washeated to 120° C. under nitrogen for 17 hrs. The reaction mixture wasdiluted with methylene chloride and washed by saturated KF aqueoussolution. The precipitation was filtered off and the filtrate wassubjected to column chromagraphy. (Silica gel, methylene chloride) toobtain the title compound (10.35 g, 60.8% yield).

Step 3: Synthesis of 3-(2,6-diphenylphenyl)-imidazo[1,2-f]phenanthridine

A 200 ml round bottom flask was charged with3-(2,6-dichlorophenyl)-imidazo[1,2-J]phenanthridine (2.1 g, 5.8 mmol),phenyl bornic acid (2.828 g, 23.4 mmol), Pd(OAc)₂ (1.127 g, 5.02 mmol),2-Dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(4.11 g, 10.03 mmol),K₃PO₄ and 70 ml of anhydrous toluene. The reaction mixture was heated to100° C. under nitrogen for 22 hrs. The reaction mixture was concentratedto dryness and subjected to column chromatography to obtain the titlecompound (1.62 g, 62% yield).

Step 4

A 25 ml 2-neck flask was charged with3-(2,6-diphenylphenyl)-imidazo[1,2-f]phenanthridine (2.93 g, 6.56 mmol).Ir(ACAC)₃ (0.643 g, 1.31 mmol) and 30 drops of tridecane. The flask wasvacuum and back refilled with nitrogen for three times and then heat to220° C. for 65 hrs. The reaction mixture was dissolved in methylenechloride and subjected to column chromatography to obtain es23 (560 mg,28% yield).

Example 27 Preparation of es101

Step 1: 2-(1H-benzo[d]imidazol-1-yl)benzonitrile 1

Benzimidazole (2.00 grams, 16.9 mmol) was dissolved in 30 mL ofanhydrous dimethylformamide. To this was added sodium hydride (0.68grams 60%, 16.9 mmol). This was stirred at ambient temperature for 30min. before addition of 1.80 mL (16.9 mmol) of 2-fluorobenzonitrile. Thereaction was stirred at 50° C. for 18 hours after which time the mixturewas cooled in an ice-water bath and diluted with 100 mL of water. Theproduct was extracted with ethyl acetate. The organic layer was washedwith water, dried over sodium sulfate and evaporated in vacuo giving thetitle compound. Mass spectral and NMR data agree with the structure.Also synthesized analogously was the 5,6-dimethyl benzimidazole analog.

Step 2: 2-(2-bromo-1H-benzo[d]imidazol-1-yl)benzonitrile 2

Compound 1 (25.75 grams, 117.5 mmol) was dissolved in dioxane (400 mL).To this was added N-bromosuccinimide (20.91 grams, 117.5 mmol). This wasstirred at reflux for 3 hours after which time the mixture was pouredinto water and the product was extracted with ethyl acetate. The organiclayer was dried over sodium sulfate, concentrated in vacuo andchromatographed (silica gel) using a mobile phase ofdichloromethane-ethyl acetate 5:1 (v/v) to provide the title compound.Mass spectral and NMR data confirm the structure. Also synthesizedanalogously was the 5,6-dimethylbenzimidazole analog.

Step 3: Synthesis of 3

Compound 2 (4.86 grams, 16.3 mmol) was stirred in 20 mL of anhydroustetrahydrofuran. To this was added 25 mL of a 1 N solution of lithiumhexamethyldisilazane in tetrahydrofuran. The reaction was stirred at 65°C. for 2.5 hours. The reaction mixture was then cooled to ambienttemperature and quenched with water. Aqueous hydrochloric acid (25 mL of1 N solution) was added and this was stirred for 10 minutes before beingneutralized with aqueous ammonium hydroxide. The resulting brown solidwas collected by filtration and dried under vacuum. Structure confirmedby mass spectral and NMR data.

Step 4: Synthesis of 4

Compound 3 (2.15 grams, 9.18 mmol) was placed in a 200 mL round bottomflask. To this was added 1,2-diiodobenzene (1.20 mL, 9.18 mmol), Copperiodide (0.52 grams, 2.75 mmol), 1,10-phenanthroline (0.50 grams, 2.75mmol) and potassium carbonate (2.66 grams, 19.28 mmol). The flask wasdegassed and backfilled with nitrogen before addition of 40 mL ofanhydrous dimethylformamide. The reaction was stirred at 150° C. for 18hours before being cooled and poured into water. The crude solid wasfiltered and chromatographed (silica gel) using a mobile phase ofdichloromethane-methanol 19:1 to give the product 4. LCMS 309.2 (ES⁺),309.2 (AP⁺); ¹H NMR (CDCl₃) δ 8.75 (m, 2H), 8.36 (d, 1H), 8.15 (d, 1H),7.95 (m, 2H), 7.81 (m, 1H), 7.56 (m, 3H), 7.44 (m, 2H).

Step 5

A 25 mL 2 neck flask was charged with 4 (0.6 g, 1.945 mmol), Ir(acac)₃(0.19 g, 0.389 mmol) and 30 drops of tridecane. The flask was evacuatedand re-filled refilled with nitrogen three times and then heated to 240C for 26 h. The resultant mixture was dissolved in methylene chlorideand subjected to silica gel column chromatography to afford es101, thestructure of which was confirmed by mass spectrometry.

Example 28 Preparation of Compound 5

Compound 3 (0.59 grams, 2.52 mmol) was stirred in 15 mL of isopropanol.To this was added sodium bicarbonate (0.42 grams, 5.04 mmol) andchloroacetaldehyde (0.50 mL 50% solution, 3.78 mmol). This was stirredat reflux for 7 hours before being cooled, diluted with water andextracted with dichloromethane. The product was purified using columnchromatography (silica gel) eluted with dichloromethane-methanol 19:1.LCMS 258.7 (AP⁺), 259.3 (ES⁺); ¹H NMR (DMSO d₆) δ 8.66 (d, 1H), 8.55 (m,1H), 8.46 (dd, 1H), 8.28 (d, 1H), 7.84 (m, 2H), 7.62 (m, 2H), 7.47 (m,2H).

Example 29 Preparation of 2-(2,4-dimethyl-1H-imidazol-1-yl)benzonitrile6

Sodium hydride (8.65 grams 60%, 0.216 mol) was stirred in 75 mL ofanhydrous dimethylformamide. To this was added dropwise a solution of2,4-dimethylimidazole (20.75 grams, 0.216 mol) in 100 mL of DMF. Afterstirring at ambient temperature for 1 hour a solution of2-fluorobenzonitrile (23.0 mL, 0.216 mol) in 75 mL of DMF was addeddropwise. This was stirred at 50° C. for 2 hours and then at ambienttemperature for 16 hours. The mixture was then poured into water and theproduct extracted with ethyl acetate. The organic layer was washed withwater and dried over sodium sulfate. The crude product waschromatographed (silica gel) and eluted with 19:1dichloromethane-methanol then 9:1 dichloromethane-methanol to afford theproduct as a solid. LCMS data confirmed structure.

Example 30 Preparation of2-(5-bromo-2,4-dimethyl-1H-imidazol-1-yl)benzonitrile 7

Compound 6 (5.18 grams, 26.0 mmol) was dissolved in acetonitrile (150mL). To this was added N-bromosuccinimide (4.67 grams, 26.0 mmol). Thiswas stirred at reflux for 1 hour before being evaporated in vacuo. Theresidue was dissolved in dichloromethane and washed with water. Theorganic layer was evaporated in vacuo to give the title compound as ayellow solid. NMR confirmed structure.

Example 31 Preparation of2-(2,4-dimethyl-5-nitro-1H-imidazol-1-yl)benzonitrile 8

Compound 6 (6.82 grams, 34.5 mmol) was added in portions totrifluoroacetic anhydride (50 mL) cooled to 0° C. After 15 minutes thesodium chloride ice water bath was replaced with a dry ice acetone bathand nitric acid (6.0 mL 70%) was added drop wise. This was stirred toambient temperature for 16 hours after which time it was pored intoice-water and neutralized with solid sodium bicarbonate. The product wasextracted with dichloromethane and purified on a silica gel flash columneluted with 49:1 dichloromethane-methanol to give the desired product asan orange paste. LCMS data supported the structure.

Example 32 Preparation of 2-(1H-pyrrol-1-yl)benzonitrile 9

Anthranilonitrile (10.0 grams, 85.0 mmol) was dissolved in 350 mL ofacetic acid. To this was added 2,5-dimethoxytetrahydrofuran (11.0 mL,85.0 mmol). This was stirred at reflux for 2 hours after which time thereaction mixture was pored into water and the product extracted withdichloromethane. The organic layer was washed with water, dried oversodium sulfate and chromatographed on a silica gel column using a mobilephase of 1:1 dichloromethane-hexane to afford the title compound as awhite solid. NMR confirms structure.

Example 33 Preparation of 2-(1H-2-bromo-pyrrol-1-yl)benzonitrile 10

Compound 9 (12.07 grams, 72.0 mmol) was dissolved in 250 mL of anhydrousdimethylformamide. This was cooled in an ice water bath. To this wasadded N-bromosuccinimide (12.77 grams, 72.0 mmol). The reaction mixturewas stirred at 0° C. for 3 hours before being poured into water. Theproduct was extracted with dichloromethane. The organic layer was washedwith water, dried over sodium sulfate and concentrated in vacuo. Thecrude product was column chromatographed (silica gel) using a mobilephase of 1:1 dichloromethane-hexane to give compound 10 as a colorlessoil. NMR and LCMS data confirmed the structure.

Example 34 Preparation of es33

To a 1 L round bottom flask was added 7-bromoimidazo[1,2,-f]phenanthridine (10 g, 33.89 mmol, prepared via the generalprocedure), piperidine (8.66 g, 101 mmol), palladium acetate (532 mg,2.37 mmol), di-tert-butylbiphenylphosphine (1.41 g, 4.74 mmol), sodiumtert-butoxide (4.56 g, 47.45 mmol) and 200 mL of anhydrous toluene. Thereaction mixture was heated to 100° C. for 14 h. After cooling, thereaction mixture was purified by chromatography on an aluminum oxidecolumn. Yield: 3.19 g.

Step 2

To a 1 L round bottom flask was added 7-piperidine-imidazo[1,2,-f]phenanthridine (2.9 g, 33.89 mmole, prepared from step 1), and 200ml of dry DMF. To this mixture with stirring, 100 mL ofN-bromosuccinimide DMF solution (1.79 g, 10.08 mmole) was added dropwiseat room temperature in the dark. The reaction mixture was continued tostir overnight. Then the mixture was poured into 1 L of water withstirring. The precipitate was collected by filtration, and furtherwashed with copious amount of water, and last with MeOH (50 mL×2), andthen dried. Yield of 3-bromo-7-piperidenyl-imidazo[1,2-f]phenanthridinewas 3.5 g.

Step 3

To a 500 mL round flask was added3-bromo-7-piperidenyl-imidazo[1,2-f]phenanthridine (3.5 g, 9.2 mmol),2,6-dimethylphenylboronic acid (8.28 g, 55.2 mmol), Pd₂(dba)₃ (4.21 g,4.6 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (S-Phos, 7.55g, 18.40 mmol), potassium phosphate tribasic (15.6 g, 73.6 mmol), and200 mL of xylene. The reaction was heated to reflux and stirred under anitrogen atmosphere for 84 hours. After cooling, the mixture waspurified by a silica gel column. Yield was 2.25 g.

Step 4

A 50 mL Schlenk tube flask was charged with3-(2,6-dimethylphenyl)-7-piperidenyl-imidazo[1,2-f]phenanthridine (1.75g, 4.32 mmol) and tris(acetylacetonate)iridium(III) (0.5 g, 1 mmol). Thereaction mixture was stirred under a nitrogen atmosphere and heated in asand bath at 240° C. for 48 hours. After cooling, the solidified mixturewas dissolved in CH₂Cl₂ and further purified by a silica gel column togive the desired compound (0.38 g)

Example 35 Preparation of es28

To a 300 ml round bottom flask was added 6-chloroimidazo[1,2,-f]phenanthridine (5 g, 19.78 mmole, prepared from the generalprocedure), pd₂(dba)₃ (1.08 g, 1.18 mmol),2-(di-cyclohexyl)phosphinobiphenyl(998 mg, 2.84 mmol), lithiumbis(trimethylsilyl)amide in THF (23.75 ml, 1 M, 23.74 ml) were added viasyringe. The reaction flask was evacuated and backfilled with nitrogen.The reaction mixture was heated to 65° C. for overnight. The reactionwas allowed to cool to room temperature, aqueous 1 M HCl (100 ml) wasadded and the reaction was stirred at room temperature for 5 min. Thenthe solution was neutralized by the addition of aqueous NaOH solution.The aqueous phase was extracted with dichloromethane three times. Theorganic layers were combined, concentrated in vacuum. The residue waspurified by flash chromatography. Yield was 1.56 g.

Step 2

To a 100 ml round bottom flask was added 6-amino-imidazo[1,2,-f]phenanthridine (100 mg, 0.42 mmol, prepared from step 1), butylaldehyde (61.84 mg, 0.85 mmol), sodium triacetoxyborohydride (272 mg,1.28 mmol) and 50 ml of methylene chloride. The reaction mixture wasstirred at room temperature for overnight. The reaction mixture wasquenched by adding aqueous saturated NaHCO₃, and the product wasextracted with EtOAC. The EtOAC layer was concentrated and yield desiredproduct (140 mg)

Step 4

A 50 mL Schlenk tube flask was charged with6-N,N-diisopropyl-imidazo[1,2-f]phenanthridine (0.45 g, 1.14 mmol) andtris(acetylacetonate)iridium(III) (0.138 g, 0.28 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givethe desired compound (0.1 g)

Example 36 Preparation of es36

Into a 500 mL 2-necked round bottom flask was placed2-bromo-4-n-hexylaniline (8.87 grams, 0.035 mol), 2-cyanophenylboronicacid pinacol ester (8.82 grams, 0.039 mol),dichlorobis(triphenylphosphine) palladium(II) (0.98 grams, 4%) andpotassium phosphate tribasic monohydrate (12.1 grams, 0.053 mol). Theflask was degassed and backfilled with nitrogen before addition oftoluene (120 mL) via syringe. The reaction was stirred at reflux forthree hours after which time the mixture was cooled to ambienttemperature. Dichloromethane (200 mL) was added and the mixture waswashed with water. The organic layer was dried over sodium sulfate,concentrated in vacuo and chromatographed (silica gel). Elution withdichloromethane-methanol 9:1 v/v yielded the desired product as a tansolid. NMR, MS confirmed structure.

Into a 250 mL round bottom flask was placed2-hexylphenanthridine-6-amine (6.17 grams, 0.022 mol),2,4,6-triisopropylphenylbromoacetaldehyde (7.93 grams, 0.024 molprepared via general procedure B) and isopropanol (50 mL). This wasstirred at reflux for 2 hours before addition of sodium bicarbonate (3.7grams, 0.044 mol). This was stirred at reflux for an additional 18hours. Water (100 mL) and dichloromethane (100 mL) were added. Thelayers were separated. The organic layer was dried over sodium sulfate,concentrated in vacuo and chromatographed (silica gel). Elution withethyl acetate-dichloromethane 1:1 v/v afforded the desired product as anorange oil which solidified on standing. ¹H NMR (CDCl₃) δ□□8.72 (d, 1H),8.37 (d, 1H), 7.64 (m, 2H), 7.36 (s, 1H), 7.19 (m, 1H), 7.14 (s, 2H),7.00 (d, 1H), 3.00 (p, 1H), 2.69 (t, 2H), 2.59 (p, 2H), 1.36 (d, 6H),1.09 (d, 6H), 0.93 (d, 6H), 0.83 (t, 3H); GC MS 504.

A 50 mL Schlenk tube flask was charged with7-hexyl-3-(2,4,6-triisopropylphenyl)imidazo[1,2-f]phenanthridine (3.9 g,7.72 mmol) and tris(acetylacetonate)iridium(III) (0.757 g, 1.54 mmol).The reaction mixture was stirred under a nitrogen atmosphere and heatedin a sand bath at 240° C. for 48 hours. After cooling, the solidifiedmixture was dissolved in CH₂Cl₂ and further purified by a silica gelcolumn to give the desired compound (0.732 g)

Example 37 General Procedure B for Imidazophenanthridine LigandSyntheses

To a 2 L 3-neck flask, equipped with mechanical stirrer, thermometer,and additional funnel, added 300 g of ice and 300 mL of H₂SO₄,2,6-diisopropyl-4-bromoaniline (46.0 g, 0.18 mol) in 200 mL of CH₃CN wasadded dropwise to this mixture while the temperature was maintainedunder 5° C. Then sodium nitrite (22.5 g, 0.32 mol) in 180 mL of ice coldwater was added dropwise while the temperature was maintained around 0°C. The resulting clear solution was slowly poured into the solution ofpotassium iodide (105 g, 0.63 mol) in 300 ml of water at roomtemperature. The mixture was stirred for 1 h. After regular work up, thecrude product was distilled at 170° C. under vacuum to afford1-iodo-2,6-diisopropyl-4-bromobenzene (60 g) as light brown soft solidupon cooling.

A 150 mL of dry toluene solution of1-iodo-2,6-diisopropyl-4-bromobenzene (17.6 g, 0.048 mol) was treatedwith n-BuLi (1.6 M in hexane, 75 mL) at −78° C. in 30 minutes. Afterstirring for 15 minutes, dry DMF (20 mL) in 50 mL of toluene was addeddropwise. The resulting mixture was slowly warmed up to roomtemperature. After regular work up, the crude product was distilled at140° C. under vacuum to afford 2,6-diisopropyl-4-bromobenzaldehyde (11.5g).

Methoxymethyl triphenylphosphonium chloride (18.68 g, 54.5 mmol) wassuspended in 200 mL of THF at −78° C. Lithium hexamethyldisilazide (1.0M in THF, 50 mL) was added dropwise. The resulting mixture was warmed upto 0° C. with stirring. After cooling the solution to −78° C.,2,6-diisopropyl-4-bromobenzaldehyde (11.5 g, 42.7 mmol) in 20 mL of THFwas added dropwise. The mixture was slowly warmed up to room temperatureand continually stirred overnight. After regular work up, the crudeproduct was distilled at 165° C. under vacuum to afford2,6-diisopropyl-4-bromo-(3-methoxystyrene (10 g). This product wasdissolved in 20 mL of dioxane and 100 mL of 18% HCl solution andrefluxed at 100° C. for 6 h. After regular work up, the crude productwas distilled at 160° C. under vacuum to afford2,6-diisopropyl-4-bromophenylacetaldehyde (7.5 g).

To a dry DMF solution of 2,6-diisopropyl-4-bromophenylacetaldehyde (7.3g, 25.8 mmol) at 0° C. was added 2,6-ditert-butyl-4-methylphenol (0.056g, 0.26 mmol), followed by NBS (4.59 g, 25.8 mmol). After stirring forfew minutes, benzenesulfonic acid (8.16 g, 51.6 mmol) was added. Theresulting mixture was stirred at 35° C. for 12 h under nitrogen. Afterregular work up, the crude product was purified by column chromatographyto afford 2-(2,6-diisopropyl-4-bromophenyl)propionaldehyde (5.4 g).

To a 500 mL round flask was added the above intermediate,2,3-dimethyl-6-aminophenanthridine (6.6 g, 30 mmol), and 100 mL of NMP.The mixture was stirred at 80° C. for 48 hours. After regular work up,the crude product was purified by a silica gel column. Yield was around1 to 2 g in different runs.

Example 38 Preparation of es32

Each step of the following procedure should be protected from light. A50 mL Schlenk tube flask was charged with3-(2,6-dimethyl-4-phenylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine(1.90 g, 4.46 mmol, obtained from3-(2,6-dimethyl-4-bromophenyl)-6,7-dimethylimidazo[1,2-f]phenanthridinethrough general method B followed by Suzuki coupling andtris(acetylacetonate)iridium(III) (0.48 g, 0.99 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees32 (0.60 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=468, 490 nm (CH₂Cl₂ solution at room temperature), CIE=(0.17,0.33).

Example 39 Preparation of es24

Each step of the following procedure should be protected from light. A50 mL Schlenk tube flask was charged with3-(2,6-diisopropylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine (2.10g, 5.17 mmol, obtained from3-(2,6-diisopropyl-4-bromophenyl)-6,7-dimethylimidazo[1,2-f]phenanthridinethrough general method B followed by treating this THF solution withn-BuLi and quenched by water at −78° C.) andtris(acetylacetonate)iridium(II) (0.56 g, 1.15 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees24 (0.54 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=458, 488 nm (CH₂Cl₂ solution at room temperature), CIE=(0.17,0.25).

Example 40 Preparation of es37

Each step of the following procedure should be protected from light. A50 mL Schlenk tube flask was charged with3-(2,6-diisopropyl-4-phenylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine(1.75 g, 3.60 mmol, obtained from3-(2,6-diisopropyl-4-bromophenyl)-6,7-dimethylimidazo[1,2-f]phenanthridinethrough general method B followed by Suzuki coupling andtris(acetylacetonate)iridium(III) (0.40 g, 0.80 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees37 (0.54 g). ¹H NMR result confirmed the desired compound. λ_(max) ofemission=456, 488 nm (CH₂Cl₂ solution at room temperature), CIE=(0.17,0.24).

Example 41 Preparation of es31

Each step of the following procedure should be protected from light. A50 mL Schlenk tube flask was charged with3-(2,4,6-triisopropylphenyl)-6,7-dimethylimidazo[1,2-f]phenanthridine(1.95 g, 4.35 mmol, obtained from general method B by using2,4,6-triisopropylbentadelhyde as starting material) andtris(acetylacetonate)iridium(III) (0.43 g, 0.96 mmol). The reactionmixture was stirred under a nitrogen atmosphere and heated in a sandbath at 240° C. for 48 hours. After cooling, the solidified mixture wasdissolved in CH₂Cl₂ and further purified by a silica gel column to givees31 (0.52 g). ¹H NMR results confirmed the desired compound. λ_(max) ofemission=460, 490 nm (CH₂Cl₂ solution at room temperature), CIE=(0.16,0.25).

Example 42 Fabrication of an OLED Device Comprising es101

An OLED device comprising es101 as the emissive compound is fabricatedaccording to procedures described by Lin et al. in U.S. patentapplication Ser. No. 11/241,981 and by Tung et al. in U.S. patentapplication Ser. No. 11/242,025 and emits blue-green light when a 10mA/cm² current is passed through the device.

Example 43 OLED Devices

OLED devices comprising dopants of the present invention were fabricatedaccording to procedures described by Lin et al. in U.S. patentapplication Ser. No. 11/241,981 and by Tung et al. in U.S. patentapplication Ser. No. 11/242,025 and gave rise to the data detailed inFIGS. 3-13, 15 and 16.

While the present invention is described with respect to particularexamples and preferred embodiments, it is understood that the presentinvention is not limited to these examples and embodiments. The presentinvention as claimed therefore includes variations from the particularexamples and preferred embodiments described herein, as will be apparentto one of skill in the art.

We claim:
 1. A phosphorescent compound comprising a metal and amonoanionic, bidentate ligand as set forth below, wherein the metal isselected from the group consisting of the non-radioactive metals withatomic numbers greater than 40, and wherein the bidentate ligand may belinked with other ligands to comprise a tridentate, tetradentate,pentadentate or hexadentate ligand;

wherein: E^(1a-q) are selected from the group consisting of C and N andcollectively comprise an 18 pi-electron system; provided that E^(1a) andE^(1p) are different; and R^(1a-i) are each, independently, H,hydrocarbyl, heteroatom substituted hydrocarbyl, cyano, fluoro, OR^(2a),SR^(2a), NR^(2a)R^(2b), BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), whereR^(2a-c) are each, independently, hydrocarbyl or heteroatom substitutedhydrocarbyl, and where any two of R^(1a-i) and R^(2a-c) may be linked toform a saturated or unsaturated, aromatic or non-aromatic ring; providedthat R^(1a-i) is other than H when attached to N, and

is excluded from the bidentate ligand.
 2. The compound of claim 1,wherein the metal is selected from the group consisting of Re, Ru, Os,Rh, Ir, Pd, Pt, and Au, and the bidentate ligand is selected from thegroup consisting of:

wherein: R^(1a-i) are each, independently, H, hydrocarbyl, heteroatomsubstituted hydrocarbyl, cyano, fluoro, OR^(2a), SR^(2a), NR^(2a)R^(2b),BR^(2a)R^(2b), or SiR^(2a)R^(2b)R^(2c), where R^(2a-c) are each,independently, hydrocarbyl or heteroatom substituted hydrocarbyl, andwhere any two of R^(1a-i) and R^(2a-c) may be linked to form a saturatedor unsaturated, aromatic or non-aromatic ring.
 3. The compound of claim2, wherein the bidentate ligand is of the formula gs1-1.
 4. The compoundof claim 2, wherein the metal is Ir or Pt.
 5. The compound of claim 1,wherein the metal is selected from the group consisting of Re, Ru, Os,Rh, Ir, Pd, Pt, and Au, and at least one of R^(1a-i) is a2,6-di-substituted aryl group.
 6. The compound of claim 5, whereinR^(1b) is a 2,6-di-substituted aryl group.
 7. The compound of claim 6,wherein the metal is Ir or Pt.
 8. The compound of claim 5, wherein the2,6-di-substituted aryl group is selected from the group consisting of2,6-dimethylphenyl; 2,4,6-trimethylphenyl; 2,6-di-isopropylphenyl;2,4,6-triisopropylphenyl; 2,6-di-isopropyl-4-phenylphenyl;2,6-dimethyl-4-phenylphenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl; 2,6-diphenylphenyl;2,6-diphenyl-4-isopropylphenyl; 2,4,6-triphenylphenyl;2,6-di-isopropyl-4-(4-isopropylphenyl)phenyl;2,6-di-isopropyl-4-(3,5-dimethylphenyl)phenyl;2,6-dimethyl-4-(2,6-dimethylpyridin-4-yl)phenyl;2,6-di-isopropyl-4-(pyridine-4-yl)phenyl; and2,6-di-(3,5-dimethylphenyl)phenyl.
 9. The compound of claim 1, whereinany two of R^(1a-i) may be linked to only form a saturated, ornon-aromatic ring.
 10. The compound of claim 2, wherein the compound isa homoleptic Ir complex.
 11. The compound of claim 2, wherein thecompound is a heteroleptic Ir complex.
 12. The compound of claim 1,wherein R^(1a-i) are each independently H, fluoro, substituted orunsubstituted C₁-C₂₀ alkyl, substituted or unsubstituted C₃-C₈cycloalkyl, or substituted or unsubstituted C₆-C₁₈ aryl; and the metalis Ir or Pt.
 13. The compound of claim 1, wherein the bidentate ligandis:


14. The compound of claim 13, wherein each of E^(1e-o) and E^(1q) iscarbon.
 15. The compound of claim 13, wherein at least one pair ofR^(1a-i) are linked to form a saturated, or non-aromatic ring
 16. Thecompound of claim 15, wherein the compound is selected from the groupconsisting of:


17. An OLED device comprising the compound of claim
 1. 18. An OLEDdevice of claim 17, wherein the metal is Ir or Pt, and R^(1b) is a2,6-di-substituted aryl group.
 19. An OLED device of claim 17, whereinthe bidentate ligand is


20. An OLED device comprising the compound of claim 3.